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• How to Write a Literature Review | Guide, Examples, & Templates

How to Write a Literature Review | Guide, Examples, & Templates

Published on January 2, 2023 by Shona McCombes . Revised on September 11, 2023.

What is a literature review? A literature review is a survey of scholarly sources on a specific topic. It provides an overview of current knowledge, allowing you to identify relevant theories, methods, and gaps in the existing research that you can later apply to your paper, thesis, or dissertation topic .

There are five key steps to writing a literature review:

• Search for relevant literature
• Evaluate sources
• Identify themes, debates, and gaps
• Outline the structure
• Write your literature review

A good literature review doesn’t just summarize sources—it analyzes, synthesizes , and critically evaluates to give a clear picture of the state of knowledge on the subject.

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Table of contents

What is the purpose of a literature review, examples of literature reviews, step 1 – search for relevant literature, step 2 – evaluate and select sources, step 3 – identify themes, debates, and gaps, step 4 – outline your literature review’s structure, step 5 – write your literature review, free lecture slides, other interesting articles, frequently asked questions, introduction.

• Quick Run-through
• Step 1 & 2

When you write a thesis , dissertation , or research paper , you will likely have to conduct a literature review to situate your research within existing knowledge. The literature review gives you a chance to:

• Demonstrate your familiarity with the topic and its scholarly context
• Develop a theoretical framework and methodology for your research
• Position your work in relation to other researchers and theorists
• Show how your research addresses a gap or contributes to a debate
• Evaluate the current state of research and demonstrate your knowledge of the scholarly debates around your topic.

Writing literature reviews is a particularly important skill if you want to apply for graduate school or pursue a career in research. We’ve written a step-by-step guide that you can follow below.

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See an example

Writing literature reviews can be quite challenging! A good starting point could be to look at some examples, depending on what kind of literature review you’d like to write.

• Example literature review #1: “Why Do People Migrate? A Review of the Theoretical Literature” ( Theoretical literature review about the development of economic migration theory from the 1950s to today.)
• Example literature review #2: “Literature review as a research methodology: An overview and guidelines” ( Methodological literature review about interdisciplinary knowledge acquisition and production.)
• Example literature review #3: “The Use of Technology in English Language Learning: A Literature Review” ( Thematic literature review about the effects of technology on language acquisition.)
• Example literature review #4: “Learners’ Listening Comprehension Difficulties in English Language Learning: A Literature Review” ( Chronological literature review about how the concept of listening skills has changed over time.)

You can also check out our templates with literature review examples and sample outlines at the links below.

Download Word doc Download Google doc

Before you begin searching for literature, you need a clearly defined topic .

If you are writing the literature review section of a dissertation or research paper, you will search for literature related to your research problem and questions .

Make a list of keywords

Start by creating a list of keywords related to your research question. Include each of the key concepts or variables you’re interested in, and list any synonyms and related terms. You can add to this list as you discover new keywords in the process of your literature search.

• Social media, Facebook, Instagram, Twitter, Snapchat, TikTok
• Body image, self-perception, self-esteem, mental health
• Generation Z, teenagers, adolescents, youth

Search for relevant sources

Use your keywords to begin searching for sources. Some useful databases to search for journals and articles include:

• Your university’s library catalogue
• Google Scholar
• Project Muse (humanities and social sciences)
• Medline (life sciences and biomedicine)
• EconLit (economics)
• Inspec (physics, engineering and computer science)

You can also use boolean operators to help narrow down your search.

Make sure to read the abstract to find out whether an article is relevant to your question. When you find a useful book or article, you can check the bibliography to find other relevant sources.

You likely won’t be able to read absolutely everything that has been written on your topic, so it will be necessary to evaluate which sources are most relevant to your research question.

For each publication, ask yourself:

• What question or problem is the author addressing?
• What are the key concepts and how are they defined?
• What are the key theories, models, and methods?
• Does the research use established frameworks or take an innovative approach?
• What are the results and conclusions of the study?
• How does the publication relate to other literature in the field? Does it confirm, add to, or challenge established knowledge?
• What are the strengths and weaknesses of the research?

Make sure the sources you use are credible , and make sure you read any landmark studies and major theories in your field of research.

You can use our template to summarize and evaluate sources you’re thinking about using. Click on either button below to download.

Take notes and cite your sources

As you read, you should also begin the writing process. Take notes that you can later incorporate into the text of your literature review.

It is important to keep track of your sources with citations to avoid plagiarism . It can be helpful to make an annotated bibliography , where you compile full citation information and write a paragraph of summary and analysis for each source. This helps you remember what you read and saves time later in the process.

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To begin organizing your literature review’s argument and structure, be sure you understand the connections and relationships between the sources you’ve read. Based on your reading and notes, you can look for:

• Trends and patterns (in theory, method or results): do certain approaches become more or less popular over time?
• Themes: what questions or concepts recur across the literature?
• Debates, conflicts and contradictions: where do sources disagree?
• Pivotal publications: are there any influential theories or studies that changed the direction of the field?
• Gaps: what is missing from the literature? Are there weaknesses that need to be addressed?

This step will help you work out the structure of your literature review and (if applicable) show how your own research will contribute to existing knowledge.

• Most research has focused on young women.
• There is an increasing interest in the visual aspects of social media.
• But there is still a lack of robust research on highly visual platforms like Instagram and Snapchat—this is a gap that you could address in your own research.

There are various approaches to organizing the body of a literature review. Depending on the length of your literature review, you can combine several of these strategies (for example, your overall structure might be thematic, but each theme is discussed chronologically).

Chronological

The simplest approach is to trace the development of the topic over time. However, if you choose this strategy, be careful to avoid simply listing and summarizing sources in order.

Try to analyze patterns, turning points and key debates that have shaped the direction of the field. Give your interpretation of how and why certain developments occurred.

If you have found some recurring central themes, you can organize your literature review into subsections that address different aspects of the topic.

For example, if you are reviewing literature about inequalities in migrant health outcomes, key themes might include healthcare policy, language barriers, cultural attitudes, legal status, and economic access.

Methodological

If you draw your sources from different disciplines or fields that use a variety of research methods , you might want to compare the results and conclusions that emerge from different approaches. For example:

• Look at what results have emerged in qualitative versus quantitative research
• Discuss how the topic has been approached by empirical versus theoretical scholarship
• Divide the literature into sociological, historical, and cultural sources

Theoretical

A literature review is often the foundation for a theoretical framework . You can use it to discuss various theories, models, and definitions of key concepts.

You might argue for the relevance of a specific theoretical approach, or combine various theoretical concepts to create a framework for your research.

Like any other academic text , your literature review should have an introduction , a main body, and a conclusion . What you include in each depends on the objective of your literature review.

The introduction should clearly establish the focus and purpose of the literature review.

Depending on the length of your literature review, you might want to divide the body into subsections. You can use a subheading for each theme, time period, or methodological approach.

As you write, you can follow these tips:

• Summarize and synthesize: give an overview of the main points of each source and combine them into a coherent whole
• Analyze and interpret: don’t just paraphrase other researchers — add your own interpretations where possible, discussing the significance of findings in relation to the literature as a whole
• Critically evaluate: mention the strengths and weaknesses of your sources
• Write in well-structured paragraphs: use transition words and topic sentences to draw connections, comparisons and contrasts

In the conclusion, you should summarize the key findings you have taken from the literature and emphasize their significance.

When you’ve finished writing and revising your literature review, don’t forget to proofread thoroughly before submitting. Not a language expert? Check out Scribbr’s professional proofreading services !

This article has been adapted into lecture slides that you can use to teach your students about writing a literature review.

Scribbr slides are free to use, customize, and distribute for educational purposes.

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If you want to know more about the research process , methodology , research bias , or statistics , make sure to check out some of our other articles with explanations and examples.

• Sampling methods
• Simple random sampling
• Stratified sampling
• Cluster sampling
• Likert scales
• Reproducibility

 Statistics

• Null hypothesis
• Statistical power
• Probability distribution
• Effect size
• Poisson distribution

Research bias

• Optimism bias
• Cognitive bias
• Implicit bias
• Hawthorne effect
• Anchoring bias
• Explicit bias

A literature review is a survey of scholarly sources (such as books, journal articles, and theses) related to a specific topic or research question .

It is often written as part of a thesis, dissertation , or research paper , in order to situate your work in relation to existing knowledge.

There are several reasons to conduct a literature review at the beginning of a research project:

• To familiarize yourself with the current state of knowledge on your topic
• To ensure that you’re not just repeating what others have already done
• To identify gaps in knowledge and unresolved problems that your research can address
• To develop your theoretical framework and methodology
• To provide an overview of the key findings and debates on the topic

Writing the literature review shows your reader how your work relates to existing research and what new insights it will contribute.

The literature review usually comes near the beginning of your thesis or dissertation . After the introduction , it grounds your research in a scholarly field and leads directly to your theoretical framework or methodology .

A literature review is a survey of credible sources on a topic, often used in dissertations , theses, and research papers . Literature reviews give an overview of knowledge on a subject, helping you identify relevant theories and methods, as well as gaps in existing research. Literature reviews are set up similarly to other  academic texts , with an introduction , a main body, and a conclusion .

An  annotated bibliography is a list of  source references that has a short description (called an annotation ) for each of the sources. It is often assigned as part of the research process for a  paper .  

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• University Libraries
• Research Guides
• Reviewing Research: Literature Reviews, Scoping Reviews, Systematic Reviews
• Differentiating the Three Review Types

Reviewing Research: Literature Reviews, Scoping Reviews, Systematic Reviews: Differentiating the Three Review Types

• Framework, Protocol, and Writing Steps
• Working with Keywords/Subject Headings
• Citing Research

The Differences in the Review Types

Grant, M.J. and Booth, A. (2009), A typology of reviews: an analysis of 14 review types and associated methodologies. H ealth Information & Libraries Journal , 26: 91-108. https://doi.org/10.1111/j.1471-1842.2009.00848.x   The objective of this study is to provide descriptive insight into the most common types of reviews, with illustrative examples from health and health information domains.

• What Type of Review is Right for you (Cornell University)

Literature Reviews

Literature Review: it is a product and a process.

As a product , it is a carefully written examination, interpretation, evaluation, and synthesis of the published literature related to your topic. It focuses on what is known about your topic and what methodologies, models, theories, and concepts have been applied to it by others.

The process is what is involved in conducting a review of the literature.

• It is ongoing
• It is iterative (repetitive)
• It involves searching for and finding relevant literature.
• It includes keeping track of your references and preparing and formatting them for the bibliography of your thesis

• Literature Reviews (University of North Carolina at Chapel Hill) This handout will explain what literature reviews are and offer insights into the form and construction of literature reviews in the humanities, social sciences, and sciences.

Scoping Reviews

Scoping reviews are a " preliminary assessment of potential size and scope of available research literature . Aims to identify nature and extent of research evidence (usually including ongoing research)." Grant and Booth (2009).

Scoping reviews are not mapping reviews: Scoping reviews are more topic based and mapping reviews are more question based.

• examining emerging evidence when specific questions are unclear - clarify definitions and conceptual boundaries
• identify and map the available evidence
• a scoping review is done prior to a systematic review
• to summarize and disseminate research findings in the research literature
• identify gaps with the intention of resolution by future publications

• Scoping review timeframe and limitations (Touro College of Pharmacy

Systematic Reviews

Many evidence-based disciplines use ‘systematic reviews," this type of review is a specific methodology that aims to comprehensively identify all relevant studies on a specific topic, and to select appropriate studies based on explicit criteria . ( https://cebma.org/faq/what-is-a-systematic-review/ )

• clearly defined search criteria
• an explicit reproducible methodology
• a systematic search of the literature with the defined criteria met
• assesses validity of the findings - no risk of bias
• a comprehensive report on the findings, apparent transparency in the results

• Better evidence for a better world Browsable collection of systematic reviews
• Systematic Reviews in the Health Sciences by Molly Maloney Last Updated Apr 4, 2024 451 views this year
• Next: Framework, Protocol, and Writing Steps >>

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Writing a Literature Review

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A literature review is a document or section of a document that collects key sources on a topic and discusses those sources in conversation with each other (also called synthesis ). The lit review is an important genre in many disciplines, not just literature (i.e., the study of works of literature such as novels and plays). When we say “literature review” or refer to “the literature,” we are talking about the research ( scholarship ) in a given field. You will often see the terms “the research,” “the scholarship,” and “the literature” used mostly interchangeably.

Where, when, and why would I write a lit review?

There are a number of different situations where you might write a literature review, each with slightly different expectations; different disciplines, too, have field-specific expectations for what a literature review is and does. For instance, in the humanities, authors might include more overt argumentation and interpretation of source material in their literature reviews, whereas in the sciences, authors are more likely to report study designs and results in their literature reviews; these differences reflect these disciplines’ purposes and conventions in scholarship. You should always look at examples from your own discipline and talk to professors or mentors in your field to be sure you understand your discipline’s conventions, for literature reviews as well as for any other genre.

A literature review can be a part of a research paper or scholarly article, usually falling after the introduction and before the research methods sections. In these cases, the lit review just needs to cover scholarship that is important to the issue you are writing about; sometimes it will also cover key sources that informed your research methodology.

Lit reviews can also be standalone pieces, either as assignments in a class or as publications. In a class, a lit review may be assigned to help students familiarize themselves with a topic and with scholarship in their field, get an idea of the other researchers working on the topic they’re interested in, find gaps in existing research in order to propose new projects, and/or develop a theoretical framework and methodology for later research. As a publication, a lit review usually is meant to help make other scholars’ lives easier by collecting and summarizing, synthesizing, and analyzing existing research on a topic. This can be especially helpful for students or scholars getting into a new research area, or for directing an entire community of scholars toward questions that have not yet been answered.

What are the parts of a lit review?

Most lit reviews use a basic introduction-body-conclusion structure; if your lit review is part of a larger paper, the introduction and conclusion pieces may be just a few sentences while you focus most of your attention on the body. If your lit review is a standalone piece, the introduction and conclusion take up more space and give you a place to discuss your goals, research methods, and conclusions separately from where you discuss the literature itself.

Introduction:

• An introductory paragraph that explains what your working topic and thesis is
• A forecast of key topics or texts that will appear in the review
• Potentially, a description of how you found sources and how you analyzed them for inclusion and discussion in the review (more often found in published, standalone literature reviews than in lit review sections in an article or research paper)
• Summarize and synthesize: Give an overview of the main points of each source and combine them into a coherent whole
• Analyze and interpret: Don’t just paraphrase other researchers – add your own interpretations where possible, discussing the significance of findings in relation to the literature as a whole
• Critically Evaluate: Mention the strengths and weaknesses of your sources
• Write in well-structured paragraphs: Use transition words and topic sentence to draw connections, comparisons, and contrasts.

Conclusion:

• Summarize the key findings you have taken from the literature and emphasize their significance
• Connect it back to your primary research question

How should I organize my lit review?

Lit reviews can take many different organizational patterns depending on what you are trying to accomplish with the review. Here are some examples:

• Chronological : The simplest approach is to trace the development of the topic over time, which helps familiarize the audience with the topic (for instance if you are introducing something that is not commonly known in your field). If you choose this strategy, be careful to avoid simply listing and summarizing sources in order. Try to analyze the patterns, turning points, and key debates that have shaped the direction of the field. Give your interpretation of how and why certain developments occurred (as mentioned previously, this may not be appropriate in your discipline — check with a teacher or mentor if you’re unsure).
• Thematic : If you have found some recurring central themes that you will continue working with throughout your piece, you can organize your literature review into subsections that address different aspects of the topic. For example, if you are reviewing literature about women and religion, key themes can include the role of women in churches and the religious attitude towards women.
• Qualitative versus quantitative research
• Empirical versus theoretical scholarship
• Divide the research by sociological, historical, or cultural sources
• Theoretical : In many humanities articles, the literature review is the foundation for the theoretical framework. You can use it to discuss various theories, models, and definitions of key concepts. You can argue for the relevance of a specific theoretical approach or combine various theorical concepts to create a framework for your research.

What are some strategies or tips I can use while writing my lit review?

Any lit review is only as good as the research it discusses; make sure your sources are well-chosen and your research is thorough. Don’t be afraid to do more research if you discover a new thread as you’re writing. More info on the research process is available in our "Conducting Research" resources .

As you’re doing your research, create an annotated bibliography ( see our page on the this type of document ). Much of the information used in an annotated bibliography can be used also in a literature review, so you’ll be not only partially drafting your lit review as you research, but also developing your sense of the larger conversation going on among scholars, professionals, and any other stakeholders in your topic.

Usually you will need to synthesize research rather than just summarizing it. This means drawing connections between sources to create a picture of the scholarly conversation on a topic over time. Many student writers struggle to synthesize because they feel they don’t have anything to add to the scholars they are citing; here are some strategies to help you:

• It often helps to remember that the point of these kinds of syntheses is to show your readers how you understand your research, to help them read the rest of your paper.
• Writing teachers often say synthesis is like hosting a dinner party: imagine all your sources are together in a room, discussing your topic. What are they saying to each other?
• Look at the in-text citations in each paragraph. Are you citing just one source for each paragraph? This usually indicates summary only. When you have multiple sources cited in a paragraph, you are more likely to be synthesizing them (not always, but often
• Read more about synthesis here.

The most interesting literature reviews are often written as arguments (again, as mentioned at the beginning of the page, this is discipline-specific and doesn’t work for all situations). Often, the literature review is where you can establish your research as filling a particular gap or as relevant in a particular way. You have some chance to do this in your introduction in an article, but the literature review section gives a more extended opportunity to establish the conversation in the way you would like your readers to see it. You can choose the intellectual lineage you would like to be part of and whose definitions matter most to your thinking (mostly humanities-specific, but this goes for sciences as well). In addressing these points, you argue for your place in the conversation, which tends to make the lit review more compelling than a simple reporting of other sources.

Literature Review vs Systematic Review

• Literature Review vs. Systematic Review
• Primary vs. Secondary Sources
• Databases and Articles
• Specific Journal or Article

Subject Guide

Definitions

It’s common to confuse systematic and literature reviews because both are used to provide a summary of the existent literature or research on a specific topic. Regardless of this commonality, both types of review vary significantly. The following table provides a detailed explanation as well as the differences between systematic and literature reviews. 

Kysh, Lynn (2013): Difference between a systematic review and a literature review. [figshare]. Available at:  http://dx.doi.org/10.6084/m9.figshare.766364

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• Next: Primary vs. Secondary Sources >>
• Last Updated: Dec 15, 2023 10:19 AM
• URL: https://libguides.sjsu.edu/LitRevVSSysRev

Literature reviews

What this guide covers, what is a literature review, literature review resources, types of literature reviews, what is the difference between a literature review and a systematic review, related information and guides, further help.

• Conducting your search
• Store and organise the literature
• Evaluate and critique the literature
• Different subject areas
• Find literature reviews

Reusing content from this guide

Attribute our work under a Creative Commons Attribution-NonCommercial 4.0 International License.

The literature review process involves a number of steps.

This guide focuses on:

• evaluating.

A literature review is a survey and critical analysis of what has been written on a particular topic, theory, question or method.

"In writing the literature review, the purpose is to explore what knowledge and ideas have been established on a topic, what approaches and viewpoints have been adopted, and what are their strengths and weaknesses."

Source: "Focus and frame". (2008). In Eriksson, P. & Kovalainen, A. Introducing Qualitative Methods: Qualitative methods in business research (pp. 44) . London: SAGE Publications Ltd. doi: 10.4135/9780857028044.

Get an overview on doing a literature review:

• Sage research methods online - Literature review methods map Information on the literature review methodology with links to further resources - the Project Planner, books, articles, videos and more.
• Ten simple rules for writing a literature review Gives 10 tips on how to approach and carry out a literature review. By Pautasso M (2013) Ten Simple Rules for Writing a Literature Review. PLoS Comput Biol9(7): e1003149.
• The literature review. In: Doing your undergraduate program This chapter looks at the purpose of literature reviews, how it is done, setting the boundaries of your search and more.

• More books on literature reviews A selection of literature review books available via UQ Library Search.

The type of literature review you do will depend on a variety of factors:

• Your discipline
• The purpose - undergraduate assessment, PHD thesis, journal article?
• Your lecturer or supervisor's requirements

Always follow the guidelines outlined by your lecturer or supervisor or consult the instructions for authors (for journal articles), when conducting your literature review.

• is an overview of the significant literature on a topic
• typically includes a critical analysis of each work included
• demonstrates the reviewers knowledge of the topic
• is a list of citations of research sources (books, journal articles, websites etc) on a topic
• includes a brief summary and analysis or evaluation of each citation = the annotation
• a critical assessment of all research studies on a particular research question
• has specific criteria for collecting and evaluating the literature
• includes a synthesis of the findings of the included studies
• This method developed by Griffith University's School of Environment bridges the gap between traditional narrative review methods and meta-analyses to enable students to produce results that are reliable, quantifiable and reproducible.

The requirements of narrative literature reviews are usually quite different than systematic reviews . However, you may be required to adopt some of the characteristics of a systematic approach when doing your literature review. Check the guidelines or criteria that have been set by your supervisor so you know what is expected of you.

Characteristics of reviews

• Meeting the review family: Exploring review types and associated information retrieval requirements This article defines different review types and discusses appropriate search methods for each type.
• Writing literature reviews - Student Support Student Support provides information on how to write effective literature reviews.
• Writing skills Learn strategies for good writing from the Graduate School.
• Systematic reviews An overview of systematic reviews and resources to support producing one.
• Subject guides See recommended resources in different subject areas.
• Grey literature Find literature that is not available in traditional channels of publishing and distribution.
• How to find guides Techniques and resources to find specific information formats.

Contact the Librarian team .

Phone: + 617 334 64312 during opening hours

Email: [email protected]

• Next: Conducting your search >>
• Last Updated: Dec 15, 2023 12:09 PM
• URL: https://guides.library.uq.edu.au/research-techniques/literature-reviews

Literature Reviews

What this handout is about.

This handout will explain what literature reviews are and offer insights into the form and construction of literature reviews in the humanities, social sciences, and sciences.

Introduction

OK. You’ve got to write a literature review. You dust off a novel and a book of poetry, settle down in your chair, and get ready to issue a “thumbs up” or “thumbs down” as you leaf through the pages. “Literature review” done. Right?

Wrong! The “literature” of a literature review refers to any collection of materials on a topic, not necessarily the great literary texts of the world. “Literature” could be anything from a set of government pamphlets on British colonial methods in Africa to scholarly articles on the treatment of a torn ACL. And a review does not necessarily mean that your reader wants you to give your personal opinion on whether or not you liked these sources.

What is a literature review, then?

A literature review discusses published information in a particular subject area, and sometimes information in a particular subject area within a certain time period.

A literature review can be just a simple summary of the sources, but it usually has an organizational pattern and combines both summary and synthesis. A summary is a recap of the important information of the source, but a synthesis is a re-organization, or a reshuffling, of that information. It might give a new interpretation of old material or combine new with old interpretations. Or it might trace the intellectual progression of the field, including major debates. And depending on the situation, the literature review may evaluate the sources and advise the reader on the most pertinent or relevant.

But how is a literature review different from an academic research paper?

The main focus of an academic research paper is to develop a new argument, and a research paper is likely to contain a literature review as one of its parts. In a research paper, you use the literature as a foundation and as support for a new insight that you contribute. The focus of a literature review, however, is to summarize and synthesize the arguments and ideas of others without adding new contributions.

Why do we write literature reviews?

Literature reviews provide you with a handy guide to a particular topic. If you have limited time to conduct research, literature reviews can give you an overview or act as a stepping stone. For professionals, they are useful reports that keep them up to date with what is current in the field. For scholars, the depth and breadth of the literature review emphasizes the credibility of the writer in his or her field. Literature reviews also provide a solid background for a research paper’s investigation. Comprehensive knowledge of the literature of the field is essential to most research papers.

Who writes these things, anyway?

Literature reviews are written occasionally in the humanities, but mostly in the sciences and social sciences; in experiment and lab reports, they constitute a section of the paper. Sometimes a literature review is written as a paper in itself.

Let’s get to it! What should I do before writing the literature review?

If your assignment is not very specific, seek clarification from your instructor:

• Roughly how many sources should you include?
• What types of sources (books, journal articles, websites)?
• Should you summarize, synthesize, or critique your sources by discussing a common theme or issue?
• Should you evaluate your sources?
• Should you provide subheadings and other background information, such as definitions and/or a history?

Find models

Look for other literature reviews in your area of interest or in the discipline and read them to get a sense of the types of themes you might want to look for in your own research or ways to organize your final review. You can simply put the word “review” in your search engine along with your other topic terms to find articles of this type on the Internet or in an electronic database. The bibliography or reference section of sources you’ve already read are also excellent entry points into your own research.

Narrow your topic

There are hundreds or even thousands of articles and books on most areas of study. The narrower your topic, the easier it will be to limit the number of sources you need to read in order to get a good survey of the material. Your instructor will probably not expect you to read everything that’s out there on the topic, but you’ll make your job easier if you first limit your scope.

Keep in mind that UNC Libraries have research guides and to databases relevant to many fields of study. You can reach out to the subject librarian for a consultation: https://library.unc.edu/support/consultations/ .

And don’t forget to tap into your professor’s (or other professors’) knowledge in the field. Ask your professor questions such as: “If you had to read only one book from the 90’s on topic X, what would it be?” Questions such as this help you to find and determine quickly the most seminal pieces in the field.

Consider whether your sources are current

Some disciplines require that you use information that is as current as possible. In the sciences, for instance, treatments for medical problems are constantly changing according to the latest studies. Information even two years old could be obsolete. However, if you are writing a review in the humanities, history, or social sciences, a survey of the history of the literature may be what is needed, because what is important is how perspectives have changed through the years or within a certain time period. Try sorting through some other current bibliographies or literature reviews in the field to get a sense of what your discipline expects. You can also use this method to consider what is currently of interest to scholars in this field and what is not.

Strategies for writing the literature review

Find a focus.

A literature review, like a term paper, is usually organized around ideas, not the sources themselves as an annotated bibliography would be organized. This means that you will not just simply list your sources and go into detail about each one of them, one at a time. No. As you read widely but selectively in your topic area, consider instead what themes or issues connect your sources together. Do they present one or different solutions? Is there an aspect of the field that is missing? How well do they present the material and do they portray it according to an appropriate theory? Do they reveal a trend in the field? A raging debate? Pick one of these themes to focus the organization of your review.

Convey it to your reader

A literature review may not have a traditional thesis statement (one that makes an argument), but you do need to tell readers what to expect. Try writing a simple statement that lets the reader know what is your main organizing principle. Here are a couple of examples:

The current trend in treatment for congestive heart failure combines surgery and medicine. More and more cultural studies scholars are accepting popular media as a subject worthy of academic consideration.

Consider organization

You’ve got a focus, and you’ve stated it clearly and directly. Now what is the most effective way of presenting the information? What are the most important topics, subtopics, etc., that your review needs to include? And in what order should you present them? Develop an organization for your review at both a global and local level:

First, cover the basic categories

Just like most academic papers, literature reviews also must contain at least three basic elements: an introduction or background information section; the body of the review containing the discussion of sources; and, finally, a conclusion and/or recommendations section to end the paper. The following provides a brief description of the content of each:

• Introduction: Gives a quick idea of the topic of the literature review, such as the central theme or organizational pattern.
• Body: Contains your discussion of sources and is organized either chronologically, thematically, or methodologically (see below for more information on each).
• Conclusions/Recommendations: Discuss what you have drawn from reviewing literature so far. Where might the discussion proceed?

Organizing the body

Once you have the basic categories in place, then you must consider how you will present the sources themselves within the body of your paper. Create an organizational method to focus this section even further.

To help you come up with an overall organizational framework for your review, consider the following scenario:

You’ve decided to focus your literature review on materials dealing with sperm whales. This is because you’ve just finished reading Moby Dick, and you wonder if that whale’s portrayal is really real. You start with some articles about the physiology of sperm whales in biology journals written in the 1980’s. But these articles refer to some British biological studies performed on whales in the early 18th century. So you check those out. Then you look up a book written in 1968 with information on how sperm whales have been portrayed in other forms of art, such as in Alaskan poetry, in French painting, or on whale bone, as the whale hunters in the late 19th century used to do. This makes you wonder about American whaling methods during the time portrayed in Moby Dick, so you find some academic articles published in the last five years on how accurately Herman Melville portrayed the whaling scene in his novel.

Now consider some typical ways of organizing the sources into a review:

• Chronological: If your review follows the chronological method, you could write about the materials above according to when they were published. For instance, first you would talk about the British biological studies of the 18th century, then about Moby Dick, published in 1851, then the book on sperm whales in other art (1968), and finally the biology articles (1980s) and the recent articles on American whaling of the 19th century. But there is relatively no continuity among subjects here. And notice that even though the sources on sperm whales in other art and on American whaling are written recently, they are about other subjects/objects that were created much earlier. Thus, the review loses its chronological focus.
• By publication: Order your sources by publication chronology, then, only if the order demonstrates a more important trend. For instance, you could order a review of literature on biological studies of sperm whales if the progression revealed a change in dissection practices of the researchers who wrote and/or conducted the studies.
• By trend: A better way to organize the above sources chronologically is to examine the sources under another trend, such as the history of whaling. Then your review would have subsections according to eras within this period. For instance, the review might examine whaling from pre-1600-1699, 1700-1799, and 1800-1899. Under this method, you would combine the recent studies on American whaling in the 19th century with Moby Dick itself in the 1800-1899 category, even though the authors wrote a century apart.
• Thematic: Thematic reviews of literature are organized around a topic or issue, rather than the progression of time. However, progression of time may still be an important factor in a thematic review. For instance, the sperm whale review could focus on the development of the harpoon for whale hunting. While the study focuses on one topic, harpoon technology, it will still be organized chronologically. The only difference here between a “chronological” and a “thematic” approach is what is emphasized the most: the development of the harpoon or the harpoon technology.But more authentic thematic reviews tend to break away from chronological order. For instance, a thematic review of material on sperm whales might examine how they are portrayed as “evil” in cultural documents. The subsections might include how they are personified, how their proportions are exaggerated, and their behaviors misunderstood. A review organized in this manner would shift between time periods within each section according to the point made.
• Methodological: A methodological approach differs from the two above in that the focusing factor usually does not have to do with the content of the material. Instead, it focuses on the “methods” of the researcher or writer. For the sperm whale project, one methodological approach would be to look at cultural differences between the portrayal of whales in American, British, and French art work. Or the review might focus on the economic impact of whaling on a community. A methodological scope will influence either the types of documents in the review or the way in which these documents are discussed. Once you’ve decided on the organizational method for the body of the review, the sections you need to include in the paper should be easy to figure out. They should arise out of your organizational strategy. In other words, a chronological review would have subsections for each vital time period. A thematic review would have subtopics based upon factors that relate to the theme or issue.

Sometimes, though, you might need to add additional sections that are necessary for your study, but do not fit in the organizational strategy of the body. What other sections you include in the body is up to you. Put in only what is necessary. Here are a few other sections you might want to consider:

• Current Situation: Information necessary to understand the topic or focus of the literature review.
• History: The chronological progression of the field, the literature, or an idea that is necessary to understand the literature review, if the body of the literature review is not already a chronology.
• Methods and/or Standards: The criteria you used to select the sources in your literature review or the way in which you present your information. For instance, you might explain that your review includes only peer-reviewed articles and journals.

Questions for Further Research: What questions about the field has the review sparked? How will you further your research as a result of the review?

Begin composing

Once you’ve settled on a general pattern of organization, you’re ready to write each section. There are a few guidelines you should follow during the writing stage as well. Here is a sample paragraph from a literature review about sexism and language to illuminate the following discussion:

However, other studies have shown that even gender-neutral antecedents are more likely to produce masculine images than feminine ones (Gastil, 1990). Hamilton (1988) asked students to complete sentences that required them to fill in pronouns that agreed with gender-neutral antecedents such as “writer,” “pedestrian,” and “persons.” The students were asked to describe any image they had when writing the sentence. Hamilton found that people imagined 3.3 men to each woman in the masculine “generic” condition and 1.5 men per woman in the unbiased condition. Thus, while ambient sexism accounted for some of the masculine bias, sexist language amplified the effect. (Source: Erika Falk and Jordan Mills, “Why Sexist Language Affects Persuasion: The Role of Homophily, Intended Audience, and Offense,” Women and Language19:2).

Use evidence

In the example above, the writers refer to several other sources when making their point. A literature review in this sense is just like any other academic research paper. Your interpretation of the available sources must be backed up with evidence to show that what you are saying is valid.

Be selective

Select only the most important points in each source to highlight in the review. The type of information you choose to mention should relate directly to the review’s focus, whether it is thematic, methodological, or chronological.

Use quotes sparingly

Falk and Mills do not use any direct quotes. That is because the survey nature of the literature review does not allow for in-depth discussion or detailed quotes from the text. Some short quotes here and there are okay, though, if you want to emphasize a point, or if what the author said just cannot be rewritten in your own words. Notice that Falk and Mills do quote certain terms that were coined by the author, not common knowledge, or taken directly from the study. But if you find yourself wanting to put in more quotes, check with your instructor.

Summarize and synthesize

Remember to summarize and synthesize your sources within each paragraph as well as throughout the review. The authors here recapitulate important features of Hamilton’s study, but then synthesize it by rephrasing the study’s significance and relating it to their own work.

Keep your own voice

While the literature review presents others’ ideas, your voice (the writer’s) should remain front and center. Notice that Falk and Mills weave references to other sources into their own text, but they still maintain their own voice by starting and ending the paragraph with their own ideas and their own words. The sources support what Falk and Mills are saying.

Use caution when paraphrasing

When paraphrasing a source that is not your own, be sure to represent the author’s information or opinions accurately and in your own words. In the preceding example, Falk and Mills either directly refer in the text to the author of their source, such as Hamilton, or they provide ample notation in the text when the ideas they are mentioning are not their own, for example, Gastil’s. For more information, please see our handout on plagiarism .

Revise, revise, revise

Draft in hand? Now you’re ready to revise. Spending a lot of time revising is a wise idea, because your main objective is to present the material, not the argument. So check over your review again to make sure it follows the assignment and/or your outline. Then, just as you would for most other academic forms of writing, rewrite or rework the language of your review so that you’ve presented your information in the most concise manner possible. Be sure to use terminology familiar to your audience; get rid of unnecessary jargon or slang. Finally, double check that you’ve documented your sources and formatted the review appropriately for your discipline. For tips on the revising and editing process, see our handout on revising drafts .

Works consulted

We consulted these works while writing this handout. This is not a comprehensive list of resources on the handout’s topic, and we encourage you to do your own research to find additional publications. Please do not use this list as a model for the format of your own reference list, as it may not match the citation style you are using. For guidance on formatting citations, please see the UNC Libraries citation tutorial . We revise these tips periodically and welcome feedback.

Anson, Chris M., and Robert A. Schwegler. 2010. The Longman Handbook for Writers and Readers , 6th ed. New York: Longman.

Jones, Robert, Patrick Bizzaro, and Cynthia Selfe. 1997. The Harcourt Brace Guide to Writing in the Disciplines . New York: Harcourt Brace.

Lamb, Sandra E. 1998. How to Write It: A Complete Guide to Everything You’ll Ever Write . Berkeley: Ten Speed Press.

Rosen, Leonard J., and Laurence Behrens. 2003. The Allyn & Bacon Handbook , 5th ed. New York: Longman.

Troyka, Lynn Quittman, and Doug Hesse. 2016. Simon and Schuster Handbook for Writers , 11th ed. London: Pearson.

You may reproduce it for non-commercial use if you use the entire handout and attribute the source: The Writing Center, University of North Carolina at Chapel Hill

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• Subject Guides

Systematic, Scoping, and Other Literature Reviews: Overview

• Project Planning

What Is a Systematic Review?

Regular literature reviews are simply summaries of the literature on a particular topic. A systematic review, however, is a comprehensive literature review conducted to answer a specific research question. Authors of a systematic review aim to find, code, appraise, and synthesize all of the previous research on their question in an unbiased and well-documented manner. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) outline the minimum amount of information that needs to be reported at the conclusion of a systematic review project. 

Other types of what are known as "evidence syntheses," such as scoping, rapid, and integrative reviews, have varying methodologies. While systematic reviews originated with and continue to be a popular publication type in medicine and other health sciences fields, more and more researchers in other disciplines are choosing to conduct evidence syntheses. 

This guide will walk you through the major steps of a systematic review and point you to key resources including Covidence, a systematic review project management tool. For help with systematic reviews and other major literature review projects, please send us an email at  [email protected] .

Getting Help with Reviews

Organization such as the Institute of Medicine recommend that you consult a librarian when conducting a systematic review. Librarians at the University of Nevada, Reno can help you:

• Understand best practices for conducting systematic reviews and other evidence syntheses in your discipline
• Choose and formulate a research question
• Decide which review type (e.g., systematic, scoping, rapid, etc.) is the best fit for your project
• Determine what to include and where to register a systematic review protocol
• Select search terms and develop a search strategy
• Identify databases and platforms to search
• Find the full text of articles and other sources
• Become familiar with free citation management (e.g., EndNote, Zotero)
• Get access to you and help using Covidence, a systematic review project management tool

Doing a Systematic Review

• Plan - This is the project planning stage. You and your team will need to develop a good research question, determine the type of review you will conduct (systematic, scoping, rapid, etc.), and establish the inclusion and exclusion criteria (e.g., you're only going to look at studies that use a certain methodology). All of this information needs to be included in your protocol. You'll also need to ensure that the project is viable - has someone already done a systematic review on this topic? Do some searches and check the various protocol registries to find out. 
• Identify - Next, a comprehensive search of the literature is undertaken to ensure all studies that meet the predetermined criteria are identified. Each research question is different, so the number and types of databases you'll search - as well as other online publication venues - will vary. Some standards and guidelines specify that certain databases (e.g., MEDLINE, EMBASE) should be searched regardless. Your subject librarian can help you select appropriate databases to search and develop search strings for each of those databases.  
• Evaluate - In this step, retrieved articles are screened and sorted using the predetermined inclusion and exclusion criteria. The risk of bias for each included study is also assessed around this time. It's best if you import search results into a citation management tool (see below) to clean up the citations and remove any duplicates. You can then use a tool like Rayyan (see below) to screen the results. You should begin by screening titles and abstracts only, and then you'll examine the full text of any remaining articles. Each study should be reviewed by a minimum of two people on the project team. 
• Collect - Each included study is coded and the quantitative or qualitative data contained in these studies is then synthesized. You'll have to either find or develop a coding strategy or form that meets your needs. 
• Explain - The synthesized results are articulated and contextualized. What do the results mean? How have they answered your research question?
• Summarize - The final report provides a complete description of the methods and results in a clear, transparent fashion. 

Adapted from

Types of reviews, systematic review.

These types of studies employ a systematic method to analyze and synthesize the results of numerous studies. "Systematic" in this case means following a strict set of steps - as outlined by entities like PRISMA and the Institute of Medicine - so as to make the review more reproducible and less biased. Consistent, thorough documentation is also key. Reviews of this type are not meant to be conducted by an individual but rather a (small) team of researchers. Systematic reviews are widely used in the health sciences, often to find a generalized conclusion from multiple evidence-based studies. 

Meta-Analysis

A systematic method that uses statistics to analyze the data from numerous studies. The researchers combine the data from studies with similar data types and analyze them as a single, expanded dataset. Meta-analyses are a type of systematic review.

Scoping Review

A scoping review employs the systematic review methodology to explore a broader topic or question rather than a specific and answerable one, as is generally the case with a systematic review. Authors of these types of reviews seek to collect and categorize the existing literature so as to identify any gaps.

Rapid Review

Rapid reviews are systematic reviews conducted under a time constraint. Researchers make use of workarounds to complete the review quickly (e.g., only looking at English-language publications), which can lead to a less thorough and more biased review. 

Narrative Review

A traditional literature review that summarizes and synthesizes the findings of numerous original research articles. The purpose and scope of narrative literature reviews vary widely and do not follow a set protocol. Most literature reviews are narrative reviews. 

Umbrella Review

Umbrella reviews are, essentially, systematic reviews of systematic reviews. These compile evidence from multiple review studies into one usable document. 

Grant, Maria J., and Andrew Booth. “A Typology of Reviews: An Analysis of 14 Review Types and Associated Methodologies.” Health Information & Libraries Journal , vol. 26, no. 2, 2009, pp. 91-108. doi: 10.1111/j.1471-1842.2009.00848.x .

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• What is a Literature Review? | Guide, Template, & Examples

What is a Literature Review? | Guide, Template, & Examples

Published on 22 February 2022 by Shona McCombes . Revised on 7 June 2022.

What is a literature review? A literature review is a survey of scholarly sources on a specific topic. It provides an overview of current knowledge, allowing you to identify relevant theories, methods, and gaps in the existing research.

There are five key steps to writing a literature review:

• Search for relevant literature
• Evaluate sources
• Identify themes, debates and gaps
• Outline the structure
• Write your literature review

A good literature review doesn’t just summarise sources – it analyses, synthesises, and critically evaluates to give a clear picture of the state of knowledge on the subject.

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Table of contents

Why write a literature review, examples of literature reviews, step 1: search for relevant literature, step 2: evaluate and select sources, step 3: identify themes, debates and gaps, step 4: outline your literature review’s structure, step 5: write your literature review, frequently asked questions about literature reviews, introduction.

• Quick Run-through
• Step 1 & 2

When you write a dissertation or thesis, you will have to conduct a literature review to situate your research within existing knowledge. The literature review gives you a chance to:

• Demonstrate your familiarity with the topic and scholarly context
• Develop a theoretical framework and methodology for your research
• Position yourself in relation to other researchers and theorists
• Show how your dissertation addresses a gap or contributes to a debate

You might also have to write a literature review as a stand-alone assignment. In this case, the purpose is to evaluate the current state of research and demonstrate your knowledge of scholarly debates around a topic.

The content will look slightly different in each case, but the process of conducting a literature review follows the same steps. We’ve written a step-by-step guide that you can follow below.

Prevent plagiarism, run a free check.

Writing literature reviews can be quite challenging! A good starting point could be to look at some examples, depending on what kind of literature review you’d like to write.

• Example literature review #1: “Why Do People Migrate? A Review of the Theoretical Literature” ( Theoretical literature review about the development of economic migration theory from the 1950s to today.)
• Example literature review #2: “Literature review as a research methodology: An overview and guidelines” ( Methodological literature review about interdisciplinary knowledge acquisition and production.)
• Example literature review #3: “The Use of Technology in English Language Learning: A Literature Review” ( Thematic literature review about the effects of technology on language acquisition.)
• Example literature review #4: “Learners’ Listening Comprehension Difficulties in English Language Learning: A Literature Review” ( Chronological literature review about how the concept of listening skills has changed over time.)

You can also check out our templates with literature review examples and sample outlines at the links below.

Download Word doc Download Google doc

Before you begin searching for literature, you need a clearly defined topic .

If you are writing the literature review section of a dissertation or research paper, you will search for literature related to your research objectives and questions .

If you are writing a literature review as a stand-alone assignment, you will have to choose a focus and develop a central question to direct your search. Unlike a dissertation research question, this question has to be answerable without collecting original data. You should be able to answer it based only on a review of existing publications.

Make a list of keywords

Start by creating a list of keywords related to your research topic. Include each of the key concepts or variables you’re interested in, and list any synonyms and related terms. You can add to this list if you discover new keywords in the process of your literature search.

• Social media, Facebook, Instagram, Twitter, Snapchat, TikTok
• Body image, self-perception, self-esteem, mental health
• Generation Z, teenagers, adolescents, youth

Search for relevant sources

Use your keywords to begin searching for sources. Some databases to search for journals and articles include:

• Your university’s library catalogue
• Google Scholar
• Project Muse (humanities and social sciences)
• Medline (life sciences and biomedicine)
• EconLit (economics)
• Inspec (physics, engineering and computer science)

You can use boolean operators to help narrow down your search:

Read the abstract to find out whether an article is relevant to your question. When you find a useful book or article, you can check the bibliography to find other relevant sources.

To identify the most important publications on your topic, take note of recurring citations. If the same authors, books or articles keep appearing in your reading, make sure to seek them out.

You probably won’t be able to read absolutely everything that has been written on the topic – you’ll have to evaluate which sources are most relevant to your questions.

For each publication, ask yourself:

• What question or problem is the author addressing?
• What are the key concepts and how are they defined?
• What are the key theories, models and methods? Does the research use established frameworks or take an innovative approach?
• What are the results and conclusions of the study?
• How does the publication relate to other literature in the field? Does it confirm, add to, or challenge established knowledge?
• How does the publication contribute to your understanding of the topic? What are its key insights and arguments?
• What are the strengths and weaknesses of the research?

Make sure the sources you use are credible, and make sure you read any landmark studies and major theories in your field of research.

You can find out how many times an article has been cited on Google Scholar – a high citation count means the article has been influential in the field, and should certainly be included in your literature review.

The scope of your review will depend on your topic and discipline: in the sciences you usually only review recent literature, but in the humanities you might take a long historical perspective (for example, to trace how a concept has changed in meaning over time).

Remember that you can use our template to summarise and evaluate sources you’re thinking about using!

Take notes and cite your sources

As you read, you should also begin the writing process. Take notes that you can later incorporate into the text of your literature review.

It’s important to keep track of your sources with references to avoid plagiarism . It can be helpful to make an annotated bibliography, where you compile full reference information and write a paragraph of summary and analysis for each source. This helps you remember what you read and saves time later in the process.

You can use our free APA Reference Generator for quick, correct, consistent citations.

To begin organising your literature review’s argument and structure, you need to understand the connections and relationships between the sources you’ve read. Based on your reading and notes, you can look for:

• Trends and patterns (in theory, method or results): do certain approaches become more or less popular over time?
• Themes: what questions or concepts recur across the literature?
• Debates, conflicts and contradictions: where do sources disagree?
• Pivotal publications: are there any influential theories or studies that changed the direction of the field?
• Gaps: what is missing from the literature? Are there weaknesses that need to be addressed?

This step will help you work out the structure of your literature review and (if applicable) show how your own research will contribute to existing knowledge.

• Most research has focused on young women.
• There is an increasing interest in the visual aspects of social media.
• But there is still a lack of robust research on highly-visual platforms like Instagram and Snapchat – this is a gap that you could address in your own research.

There are various approaches to organising the body of a literature review. You should have a rough idea of your strategy before you start writing.

Depending on the length of your literature review, you can combine several of these strategies (for example, your overall structure might be thematic, but each theme is discussed chronologically).

Chronological

The simplest approach is to trace the development of the topic over time. However, if you choose this strategy, be careful to avoid simply listing and summarising sources in order.

Try to analyse patterns, turning points and key debates that have shaped the direction of the field. Give your interpretation of how and why certain developments occurred.

If you have found some recurring central themes, you can organise your literature review into subsections that address different aspects of the topic.

For example, if you are reviewing literature about inequalities in migrant health outcomes, key themes might include healthcare policy, language barriers, cultural attitudes, legal status, and economic access.

Methodological

If you draw your sources from different disciplines or fields that use a variety of research methods , you might want to compare the results and conclusions that emerge from different approaches. For example:

• Look at what results have emerged in qualitative versus quantitative research
• Discuss how the topic has been approached by empirical versus theoretical scholarship
• Divide the literature into sociological, historical, and cultural sources

Theoretical

A literature review is often the foundation for a theoretical framework . You can use it to discuss various theories, models, and definitions of key concepts.

You might argue for the relevance of a specific theoretical approach, or combine various theoretical concepts to create a framework for your research.

Like any other academic text, your literature review should have an introduction , a main body, and a conclusion . What you include in each depends on the objective of your literature review.

The introduction should clearly establish the focus and purpose of the literature review.

If you are writing the literature review as part of your dissertation or thesis, reiterate your central problem or research question and give a brief summary of the scholarly context. You can emphasise the timeliness of the topic (“many recent studies have focused on the problem of x”) or highlight a gap in the literature (“while there has been much research on x, few researchers have taken y into consideration”).

Depending on the length of your literature review, you might want to divide the body into subsections. You can use a subheading for each theme, time period, or methodological approach.

As you write, make sure to follow these tips:

• Summarise and synthesise: give an overview of the main points of each source and combine them into a coherent whole.
• Analyse and interpret: don’t just paraphrase other researchers – add your own interpretations, discussing the significance of findings in relation to the literature as a whole.
• Critically evaluate: mention the strengths and weaknesses of your sources.
• Write in well-structured paragraphs: use transitions and topic sentences to draw connections, comparisons and contrasts.

In the conclusion, you should summarise the key findings you have taken from the literature and emphasise their significance.

If the literature review is part of your dissertation or thesis, reiterate how your research addresses gaps and contributes new knowledge, or discuss how you have drawn on existing theories and methods to build a framework for your research. This can lead directly into your methodology section.

A literature review is a survey of scholarly sources (such as books, journal articles, and theses) related to a specific topic or research question .

It is often written as part of a dissertation , thesis, research paper , or proposal .

There are several reasons to conduct a literature review at the beginning of a research project:

• To familiarise yourself with the current state of knowledge on your topic
• To ensure that you’re not just repeating what others have already done
• To identify gaps in knowledge and unresolved problems that your research can address
• To develop your theoretical framework and methodology
• To provide an overview of the key findings and debates on the topic

Writing the literature review shows your reader how your work relates to existing research and what new insights it will contribute.

The literature review usually comes near the beginning of your  dissertation . After the introduction , it grounds your research in a scholarly field and leads directly to your theoretical framework or methodology .

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What is a Literature Review?

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Learn the basics about writing a literature review

If you've ever written a research paper , it's likely you've done some form of literature review. A literature review is a survey of current books and articles on a particular topic. While they may sound tedious, literature reviews are helpful windows into the cutting edge of any field.

Literature reviews are often closely associated with annotated bibliographies, which also list and analyze scholarly sources. However, unlike an annotated bibliography, a literature review is usually written in the form of an essay, with full paragraphs, an introduction, and a conclusion. Literature reviews also differ from book reviews , despite their similar names, since they focus on bodies of work rather than singular sources.

Why are literature reviews important?

Doing a literature review is the first step to writing a great research paper. Whether you know a lot about a topic or only a little, a literature review will help familiarize you with the most important scholars, themes, and sources in the field.

Writing a literature review can also help you build a solid thesis before you tackle the rest of an essay. Even if you've selected an interesting topic, articulating a great argument can be trickier than you think. Often, students realize that their thesis is untenable halfway through writing their papers, usually because there aren't enough sources to support their arguments. By carrying out a literature review, you'll build an inventory of research that you can use at any point in the writing process.

Since most researchers draw on networks of other scholarship, reviewing literature can also help you find sources that you didn't know about before. For example, the citations in a journal article or book often direct you to seminal works in the field. Even if you can't read every last paper, a literature review will leave you better informed about where to turn if you need more information.

What are the stages of writing a literature review?

Poring over books and articles for a literature review takes some dedication. By dividing up your work into four different steps, you'll save time and finish your review faster.

1) Research

A thorough amount of research is a prerequisite for writing a good literature review. In the research stage, you should visit a library or browse a journal database to begin collecting your sources. Start by searching for a broad topic and hone in on your research question as you become more confident about your subject.

2) Consolidation of information

Next, you should compile all the information that you've gleaned from your research. Aim to organize your notes in a way that's logical, such as thematically or chronologically. It may be helpful to use visual aids, such as charts or graphs, to keep track of all the sources you’ve surveyed. For every book or article, make note of the full author's name, title, and publishing information, so that you can use these details in your bibliography .

3) Analysis

Now you can go back over the data that you've collected and look for connections between sources and your research question. You can also expand your notes from the consolidation phase and categorize each source by the author's main argument and type of evidence. This will help simplify your analysis and make it easier to draw conclusions in your literature review.

4) Presentation

The final stage is when you put everything you know onto paper. Introduce readers to your research question and lead them through existing scholarly works, starting with the most impactful and important sources. Don’t forget to write an introduction , make transitions between paragraphs, and present a conclusion. 

Putting the final touches on your literature review

After reading our guide, you may still have questions about perfecting your literature review. Our academic editors are happy to help—don't hesitate to contact us!

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Literature Reviews

• What is a literature review?
• Steps in the Literature Review Process
• Define your research question
• Determine inclusion and exclusion criteria
• Choose databases and search
• Review Results
• Synthesize Results
• Analyze Results
• Librarian Support

What is a Literature Review?

A literature or narrative review is a comprehensive review and analysis of the published literature on a specific topic or research question. The literature that is reviewed contains: books, articles, academic articles, conference proceedings, association papers, and dissertations. It contains the most pertinent studies and points to important past and current research and practices. It provides background and context, and shows how your research will contribute to the field. 

A literature review should: 

• Provide a comprehensive and updated review of the literature;
• Explain why this review has taken place;
• Articulate a position or hypothesis;
• Acknowledge and account for conflicting and corroborating points of view

From  S age Research Methods

Purpose of a Literature Review

A literature review can be written as an introduction to a study to:

• Demonstrate how a study fills a gap in research
• Compare a study with other research that's been done

Or it can be a separate work (a research article on its own) which:

• Organizes or describes a topic
• Describes variables within a particular issue/problem

Limitations of a Literature Review

Some of the limitations of a literature review are:

• It's a snapshot in time. Unlike other reviews, this one has beginning, a middle and an end. There may be future developments that could make your work less relevant.
• It may be too focused. Some niche studies may miss the bigger picture.
• It can be difficult to be comprehensive. There is no way to make sure all the literature on a topic was considered.
• It is easy to be biased if you stick to top tier journals. There may be other places where people are publishing exemplary research. Look to open access publications and conferences to reflect a more inclusive collection. Also, make sure to include opposing views (and not just supporting evidence).

Source: Grant, Maria J., and Andrew Booth. “A Typology of Reviews: An Analysis of 14 Review Types and Associated Methodologies.” Health Information & Libraries Journal, vol. 26, no. 2, June 2009, pp. 91–108. Wiley Online Library, doi:10.1111/j.1471-1842.2009.00848.x.

Meryl Brodsky : Communication and Information Studies

Hannah Chapman Tripp : Biology, Neuroscience

Carolyn Cunningham : Human Development & Family Sciences, Psychology, Sociology

Larayne Dallas : Engineering

Janelle Hedstrom : Special Education, Curriculum & Instruction, Ed Leadership & Policy ​

Susan Macicak : Linguistics

Imelda Vetter : Dell Medical School

For help in other subject areas, please see the guide to library specialists by subject .

Periodically, UT Libraries runs a workshop covering the basics and library support for literature reviews. While we try to offer these once per academic year, we find providing the recording to be helpful to community members who have missed the session. Following is the most recent recording of the workshop, Conducting a Literature Review. To view the recording, a UT login is required.

• October 26, 2022 recording
• Last Updated: Oct 26, 2022 2:49 PM
• URL: https://guides.lib.utexas.edu/literaturereviews

How to Write a Literature Review

• What is a literature review

How is a literature review different from a research paper?

• What should I do before starting my literature review?
• What type of literature review should I write and how should I organize it?
• What should I be aware of while writing the literature review?
• For more information on Literature Reviews
• More Research Help

The purpose of an academic research paper is to develop a new argument. The literature review is one part of a research paper. In a research paper, you use the literature review as a foundation and as support for the new insight that you contribute. The focus of a literature review, however, is to summarize and analyze the arguments and ideas of others without adding new contributions.

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Literature Searching

Literature Searching vs. Literature Review

You may hear about conducting a literature search and literature review inter-changeably. In general, a literature search is the process of seeking out and identifying the existing literature related to a topic or question of interest, while a literature review is the organized synthesis of the information found in the existing literature.

In research, a literature search is typically the first step of a literature review. The search identifies relevant existing studies and articles, and the review is the end result of analyzing, synthesizing, and organizing the information found in the search.

When writing a research paper, the literature review gives you a chance to:

• Demonstrate your familiarity with the topic and its scholarly context
• Develop a theoretical framework and methodology for your research
• Show how your research addresses a knowledge gap or contributes to a debate
• Evaluate the current state of research and demonstrate your knowledge of the scholarly debates around your topic. 

References/Additional Resources

  Baker, J. D. (2016). T he Purpose, Process, and Methods of Writing a Literature Review . AORN Journal, 103(3), 265–269.

  Patrick, L. J., & Munro, S. (2004). The Literature Review: Demystifying the Literature Search. The Diabetes Educator, 30(1), 30–38. 

• << Previous: Home
• Next: Major Steps in a Literature Search >>

What Is A Literature Review?

A plain-language explainer (with examples).

By:  Derek Jansen (MBA) & Kerryn Warren (PhD) | June 2020 (Updated May 2023)

If you’re faced with writing a dissertation or thesis, chances are you’ve encountered the term “literature review” . If you’re on this page, you’re probably not 100% what the literature review is all about. The good news is that you’ve come to the right place.

Literature Review 101

• What (exactly) is a literature review
• What’s the purpose of the literature review chapter
• How to find high-quality resources
• How to structure your literature review chapter
• Example of an actual literature review

What is a literature review?

The word “literature review” can refer to two related things that are part of the broader literature review process. The first is the task of  reviewing the literature  – i.e. sourcing and reading through the existing research relating to your research topic. The second is the  actual chapter  that you write up in your dissertation, thesis or research project. Let’s look at each of them:

Reviewing the literature

The first step of any literature review is to hunt down and  read through the existing research  that’s relevant to your research topic. To do this, you’ll use a combination of tools (we’ll discuss some of these later) to find journal articles, books, ebooks, research reports, dissertations, theses and any other credible sources of information that relate to your topic. You’ll then  summarise and catalogue these  for easy reference when you write up your literature review chapter. 

The literature review chapter

The second step of the literature review is to write the actual literature review chapter (this is usually the second chapter in a typical dissertation or thesis structure ). At the simplest level, the literature review chapter is an  overview of the key literature  that’s relevant to your research topic. This chapter should provide a smooth-flowing discussion of what research has already been done, what is known, what is unknown and what is contested in relation to your research topic. So, you can think of it as an  integrated review of the state of knowledge  around your research topic. 

What’s the purpose of a literature review?

The literature review chapter has a few important functions within your dissertation, thesis or research project. Let’s take a look at these:

Purpose #1 – Demonstrate your topic knowledge

The first function of the literature review chapter is, quite simply, to show the reader (or marker) that you  know what you’re talking about . In other words, a good literature review chapter demonstrates that you’ve read the relevant existing research and understand what’s going on – who’s said what, what’s agreed upon, disagreed upon and so on. This needs to be  more than just a summary  of who said what – it needs to integrate the existing research to  show how it all fits together  and what’s missing (which leads us to purpose #2, next). 

Purpose #2 – Reveal the research gap that you’ll fill

The second function of the literature review chapter is to  show what’s currently missing  from the existing research, to lay the foundation for your own research topic. In other words, your literature review chapter needs to show that there are currently “missing pieces” in terms of the bigger puzzle, and that  your study will fill one of those research gaps . By doing this, you are showing that your research topic is original and will help contribute to the body of knowledge. In other words, the literature review helps justify your research topic.  

Purpose #3 – Lay the foundation for your conceptual framework

The third function of the literature review is to form the  basis for a conceptual framework . Not every research topic will necessarily have a conceptual framework, but if your topic does require one, it needs to be rooted in your literature review. 

For example, let’s say your research aims to identify the drivers of a certain outcome – the factors which contribute to burnout in office workers. In this case, you’d likely develop a conceptual framework which details the potential factors (e.g. long hours, excessive stress, etc), as well as the outcome (burnout). Those factors would need to emerge from the literature review chapter – they can’t just come from your gut! 

So, in this case, the literature review chapter would uncover each of the potential factors (based on previous studies about burnout), which would then be modelled into a framework. 

Purpose #4 – To inform your methodology

The fourth function of the literature review is to  inform the choice of methodology  for your own research. As we’ve  discussed on the Grad Coach blog , your choice of methodology will be heavily influenced by your research aims, objectives and questions . Given that you’ll be reviewing studies covering a topic close to yours, it makes sense that you could learn a lot from their (well-considered) methodologies.

So, when you’re reviewing the literature, you’ll need to  pay close attention to the research design , methodology and methods used in similar studies, and use these to inform your methodology. Quite often, you’ll be able to  “borrow” from previous studies . This is especially true for quantitative studies , as you can use previously tried and tested measures and scales. 

How do I find articles for my literature review?

Finding quality journal articles is essential to crafting a rock-solid literature review. As you probably already know, not all research is created equally, and so you need to make sure that your literature review is  built on credible research . 

We could write an entire post on how to find quality literature (actually, we have ), but a good starting point is Google Scholar . Google Scholar is essentially the academic equivalent of Google, using Google’s powerful search capabilities to find relevant journal articles and reports. It certainly doesn’t cover every possible resource, but it’s a very useful way to get started on your literature review journey, as it will very quickly give you a good indication of what the  most popular pieces of research  are in your field.

One downside of Google Scholar is that it’s merely a search engine – that is, it lists the articles, but oftentimes  it doesn’t host the articles . So you’ll often hit a paywall when clicking through to journal websites. 

Thankfully, your university should provide you with access to their library, so you can find the article titles using Google Scholar and then search for them by name in your university’s online library. Your university may also provide you with access to  ResearchGate , which is another great source for existing research. 

Remember, the correct search keywords will be super important to get the right information from the start. So, pay close attention to the keywords used in the journal articles you read and use those keywords to search for more articles. If you can’t find a spoon in the kitchen, you haven’t looked in the right drawer. 

Need a helping hand?

How should I structure my literature review?

Unfortunately, there’s no generic universal answer for this one. The structure of your literature review will depend largely on your topic area and your research aims and objectives.

You could potentially structure your literature review chapter according to theme, group, variables , chronologically or per concepts in your field of research. We explain the main approaches to structuring your literature review here . You can also download a copy of our free literature review template to help you establish an initial structure.

In general, it’s also a good idea to start wide (i.e. the big-picture-level) and then narrow down, ending your literature review close to your research questions . However, there’s no universal one “right way” to structure your literature review. The most important thing is not to discuss your sources one after the other like a list – as we touched on earlier, your literature review needs to synthesise the research , not summarise it .

Ultimately, you need to craft your literature review so that it conveys the most important information effectively – it needs to tell a logical story in a digestible way. It’s no use starting off with highly technical terms and then only explaining what these terms mean later. Always assume your reader is not a subject matter expert and hold their hand through a journe y of the literature while keeping the functions of the literature review chapter (which we discussed earlier) front of mind.

Example of a literature review

In the video below, we walk you through a high-quality literature review from a dissertation that earned full distinction. This will give you a clearer view of what a strong literature review looks like in practice and hopefully provide some inspiration for your own. 

Wrapping Up

In this post, we’ve (hopefully) answered the question, “ what is a literature review? “. We’ve also considered the purpose and functions of the literature review, as well as how to find literature and how to structure the literature review chapter. If you’re keen to learn more, check out the literature review section of the Grad Coach blog , as well as our detailed video post covering how to write a literature review . 

Psst… there’s more!

This post is an extract from our bestselling short course, Literature Review Bootcamp . If you want to work smart, you don't want to miss this .

You Might Also Like:

16 Comments

Thanks for this review. It narrates what’s not been taught as tutors are always in a early to finish their classes.

Thanks for the kind words, Becky. Good luck with your literature review 🙂

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This is review is amazing. I benefited from it a lot and hope others visiting this website will benefit too.

Timothy T. Chol [email protected]

Thank you very much for the guiding in literature review I learn and benefited a lot this make my journey smooth I’ll recommend this site to my friends

This was so useful. Thank you so much.

Hi, Concept was explained nicely by both of you. Thanks a lot for sharing it. It will surely help research scholars to start their Research Journey.

The review is really helpful to me especially during this period of covid-19 pandemic when most universities in my country only offer online classes. Great stuff

Great Brief Explanation, thanks

So helpful to me as a student

GradCoach is a fantastic site with brilliant and modern minds behind it.. I spent weeks decoding the substantial academic Jargon and grounding my initial steps on the research process, which could be shortened to a couple of days through the Gradcoach. Thanks again!

This is an amazing talk. I paved way for myself as a researcher. Thank you GradCoach!

Well-presented overview of the literature!

This was brilliant. So clear. Thank you

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Getting Started With Library Research: Literature Review

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What is a Literature Review?

A  literature review  is a comprehensive study and interpretation of literature that addresses a specific topic.

Literature reviews are generally conducted in one of two ways:

1) As a preliminary review before a larger study in order to critically evaluate the current literature and justify why further study and research is required.

2) As a project in itself that provides a comprehensive survey of the works published in a particular discipline or area of research over a specified period of time.  

Why conduct a literature review? They provide you with a handy guide to a particular topic. If you have limited time to conduct research, literature reviews can give you an overview or act as a stepping stone.

More:   different types of literature reviews  on how to conduct a literature review.

Literature Review Links

• PhD on Track: Types of Reviews Narrative & Systematic
• Purdue Owl: Literature Reviews
• Purdue OWL: Writing a Literature Review

How to Develop a Literature Review

How to develop a literature review from Academic Research Foundations: Quantitative by Rolin Moe

What is the Difference Between a Systematic Review and a Meta-analysis?

Dr. Singh discusses the difference between a systematic review and a meta-analysis.

Purpose of a Literature Review

Purpose of a literature review from Academic Research Foundations: Quantitative by Rolin Moe

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• Next: Literature Review >>
• Last Updated: Mar 11, 2024 1:18 PM
• URL: https://libguides.kettering.edu/Library_Research

• Introduction
• Welcome to Advanced Writing!
• Author Biographies
• Acknowledgments
• UNIT 1. WRITING TOOLS
• 1. What's Advanced About Advanced Writing?
• 2. Writing Tools
• 3. Writing Processes
• 4. Grammar & Mechanics
• UNIT 2. ACADEMIC AUDIENCES
• 7. Writing for Academic Audiences
• 8. Finding & Evaluating Sources
• 9. Discussing & Citing Sources
• 10. Defining Literature Reviews
• 11. Planning Literature Reviews
• 12. Writing Literature Reviews
• 13. Crafting Proposals
• UNIT 3. GENERAL AUDIENCES
• 14. Writing for General Audiences
• 15. Applying for Jobs & Graduate Schools
• 16. Creating Public Texts
• 17. Presenting
• Translations

Defining Literature Reviews

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Learning Outcomes

In this chapter, you'll

• learn the definition of a literature review
• understand the difference between a literature review and a traditional argumentative research paper
• learn how literature reviews are used in the scholarly research process
• understand the purpose of a literature review

10.1 What's a Literature Review?

To answer this question, I have to tell you a story, so stick with me.

The straightforward answer is that a literature review  is a review or synthesis of all the research published on a certain topic. But I'd rather explain it from a skateboarder's perspective:

One of my favorite movie series is the 1980s classic Back to the Future trilogy where the bodacious skater Marty McFly time-travels to the future and sees the coolest thing I could imagine: a hoverboard. As a kid, I was a dabbling skateboarder at the time I saw this movie and thought if I could just have one of those rad, flying hoverboards, all my troubles would disappear. It was an optimistic time.

Trouble is, hoverboards are really hard to make. We've already passed the year 2015 when the "Future" of Back to the Future Part 2 takes place, and guess what? No hoverboards. I know what you're thinking: you've seen a skateboard-like, two-wheeled device marketed with the name "Hoverboard" that teenagers ride around parks, sidewalks, and their parents' basements. But you're wrong: that's just an electric, no-handled scooter that occasionally catches on fire and burns people's houses down. I'm not satisfied.

I want a real hoverboard. That you ride in the air . So how can we know when real hoverboards will be available? How can we know where the technology is now? Will we know a real hoverboard when we see one? Tony Hawk, the best skateboarder of all time (whose face was incidentally taped to my wall in the '80s) recently filmed a 2-minute video of how far real hoverboard technology has come—filmed on the very day Marty McFly supposedly went to the future: October 21, 2015:

Tony Hawk and the cutting edge of hoverboard research

Although this "hoverboard" was really a huge black rectangle the size of Delaware floating only an inch off the ground, and although Tony Hawk fell off a lot, he was technically in the air, so I'm taking that as a good sign. Then recently, a professional jet ski rider broke the world record for longest time "hovering" in the air with a highly dangerous jet-engine-propelled contraption called Flyboard Air. It's also definitely a step in the right direction, but there's a big problem (beside extreme danger): it's projected to cost around $250,000. Sadly, not in my price range.

The good news is, now we've found the point where hoverboard research actually is. The bad news: we have to face the sad truth that it might still be a while before we get real Marty-McFly-approved flying hoverboards that non-billionaires can ride. But at least now we know. Because knowing is half the battle.

The State of a Field on a Topic

That leads me to literature reviews. Whenever you want to know the state of a field of research like how far hoverboard technology has come, the best way to find out is probably not YouTube videos. It turns out you can do something much more reliable: conduct a literature review . In this case, "literature" doesn't mean the Victorian novels you read in English class, it means all the research published on a certain topic. So a literature review is simply a review or a synthesis of the research published on a topic.

Researchers and companies today don't just start projects out of the blue—they do their homework first by finding out what others have already done. So if you want to make a hoverboard, you don't just go to Home Depot and buy random parts—you research what already exists and talk to the experts so you don't have to reinvent the wheel (get it?).

"If I have seen further, it is by standing on the shoulders of giants." —Sir Isaac Newton (and the motto of Google Scholar)

Before good researchers set up any surveys or experiments, or even write a proposal for funding, they figure out exactly which research questions have already been asked and answered. Same goes for anyone wanting to make a product that will sell. But more importantly, they look for the gaps  in the research or marketplace where answers have yet to be found. And then they focus their own work on filling in some of those gaps. That'll be your job, too.

In other words, the goal of a literature review is to find the sweet spot where the most promising research is happening now—we call that the cutting edge. ( The Cutting Edge is also a cheesy '90s movie about ice skating, so be sure not to get them confused.) As Marty McFly would say, finding the cutting edge is pretty gnarly because that's where the adventure begins. So grab the closest thing you have to a hoverboard, and let's go.

10.2 How is a Literature Review different from a typical Research Paper?

*Suggestion: Just for fun, as you read this next section, set the mood by playing one of these songs called "Old Friends." You'll see how it's relevant in a minute.

Simon & Garfunkel "Old Friends" —old-school classic

Ben Rector "Old Friends" —w/ high school band Euromart, in the garage of the house he grew up in

Willie Nelson, Roger Miller, Ray Price “Old Friends” —country Western style

You've probably been writing research papers most of your life—you know, starting from the five-paragraph essay you learned in high school to the term paper you wrote last semester that had a thesis statement and lots of quotes. So it can seem daunting to switch gears to writing a literature review, but there are some distinct advantages to making the switch (that I'll get to later). The trick is first understanding the difference between the two.

Research Papers are Thesis Driven

The difference between a typical research paper and a literature review is your purpose and strategy. Tell me if this sounds familiar: when you're assigned to write a research paper, you start with a thesis or argument that you'd like to make. Your thesis has to do with a new way to look at something or a change you'd like to see in the future. Then you search for sources that support your point. You might adjust your thesis if you come across sources that challenge your claim, but generally, the sources you've gathered become evidence for your thesis and you use them to support your point. In other words, your argumentative research paper is driven by your thesis .

Literature Reviews are Source Driven

In contrast, when you write a Literature Review, the sources themselves dictate what you'll say in your paper. Remember, your goal is to tell your audience the state of the field on a topic—what's been happening in the published research—so you can find the cutting edge and where the research gaps are. Therefore, you need to find and evaluate the most relevant sources surrounding a topic and then write a review based on what you find . You can't decide on a thesis statement or know what points you'll make before you start because you have to find out what researchers are doing before you can report on that. Simply put, your literature review is driven by your sources .

You'll still have an overarching point/thesis that controls your literature review paper structure, but it will be a claim about what patterns you found in the research— not an argument about a change you want to see in the future or a new way to look at something. And you'll decide on your thesis much later in the writing process. Here's a table that compares the writing process of a traditional research paper with that of a literature review:

Literature Reviews: Catching up with Old Friends

Here's where the song comes in—another way to think about the difference between literature reviews and the traditional research papers you're used to writing (with props to Professor David Taylor from the University of Maryland ). What do you do when you meet an old friend? You ask,

"How are you? What have you been up to? Fill me in!"

Literature Reviews are like getting filled in by an old friend . Only this time, you're explaining how a field of research has gotten to the present (like how far hoverboard technology has come). But like a conversation with an old friend, you want to review only the details most relevant to the situation. You don't usually give a moment-by-moment chronology of what you've done in your life (no one has time for that); rather, you talk in terms of categories—work, family, travel, etc. This is like the synthesis that happens in a Literature Review. As you read sources about a specific topic, you'll look for themes, for similarities and differences, for points of agreement and disagreement, for gaps in the research that haven't been filled in yet. Those themes become the categories you'll talk about in your literature review so your audience will understand the big picture about your topic.

Why Literature Reviews?

There are some huge advantages to trying out this new genre of a literature review as opposed to a traditional research paper. We learned in Chapter 9 Talking About Sources that most college students do not engage with their sources—most students merely find quotes to fit their argument and plug them into their papers without actually understanding—or perhaps even reading—their sources. Many even quote directly from the abstract, not even bothering to read past there. Even more telling is that in the Howard and Jamieson study mentioned in Chapter 9, the number of students who summarized their sources in their papers was only 6%. That's probably because summary is a higher-level task that requires actually understanding the sources instead of merely extracting one quote at a time. And without summary, you can't have synthesis—the cornerstone of a good literature review. It's as if students are spending a lot of time exercising their research muscles, but have completely missed their most essential summary and synthesis muscles—their core, if you will.

Because of findings like this, many instructors are now assigning literature review papers rather than traditional research papers in order to isolate those core muscles that need exercise the most—the summarizing and synthesizing muscles. Because Literature Reviews are source-driven and require understanding and summarizing many sources, they are the perfect assignment for strengthening the missing skills in your writing repertoire. We've found that when our students write literature reviews, they learn (sometimes for the first time) the true steps of the research process; how to read, understand, and summarize sources; and even more importantly, they can finally see the big picture and synthesize those sources to understand the state of a field.

And by strengthening your ability to evaluate and synthesize sources, you'll actually strengthen your other writing skills as well, including your traditional research paper writing skills. You'll find after you focus on the literature review that finding and evaluating any type of source will be much easier—just like strengthening your core muscles will help you with all types of exercise.

This might sound crazy, but I actually get emails every semester from former students thanking me for assigning them a literature review because it's helped them with research projects in their next classes or jobs. You, too, can get rock hard research abs by learning how to write a literature review!

10.3 Literature Reviews in the Real World

In case you're not convinced enough to take on the task of writing a literature review, I thought I'd mention that literature reviews come up in the real world in many different venues that you'll encounter in your schooling and career. You'll see that they often follow similar patterns and purposes:

Grant Proposals

Any grant proposal submitted to request research funding begins with an extensive literature review to justify the need for the research funds. If you can prove there's a gap in knowledge, it makes it that much easier to convince your audience to give you funding to fill that gap. More on that in Chapter 12: Proposals .

IMRAD Articles

IMRAD (pronounced "im-rad") stands for Introduction, Methods, Results, and Discussion and is the most common genre published in the social sciences and sciences. Most of the sources you gather will likely be IMRAD-format papers or will at least begin with an introduction. The "I" in IMRAD stands for Introduction and usually consists of a review of the literature on the authors' research topic. The author(s) usually use the Introduction section to report on the published literature about their research topic and reveal the trends and gaps in current research. An added benefit to beginning an article this way is that by showing the gaps in the research, the author(s) can justify their own research and explain the significance of the topic they chose to examine. Clever!

It's kind of like a superhero moment when someone publishes that they have a problem (e.g., turns on the Bat Signal or yells "Help!"), and Batman or Superman or Wonder Woman swoops in and saves the day. The authors lay bare a problem or gap in current research, and then they reveal the research they did to solve that problem, fill that gap. Ta da! Research saves the day. 

As you might guess, the sections following the Introduction (Methods, Results, Discussion) describe the primary research the author(s) conducted to answer their research question. First they report on their quantitative and/or qualitative M ethods (M in IMRAD) including statistical analyses. Then they publish their R esults (R in IMRAD). Finally, the author(s) embark on a D iscussion (D in IMRAD) of their results in the context of the greater field of research and make suggestions for future research. This starts the research cycle over again as someone else reads their article as part of their own review of the literature and discovers a gap in the research that can be filled by new primary research. 

Published Literature Reviews

In the world of academia, literature reviews can also be published on their own. For example, if someone does an extensive  investigation into an important topic, the publishers of academic journals will often publish that literature review on its own to help other researchers understand that topic better. 

Market Analyses

Popular literature reviews.

Lest you think nerdy academics and business gurus are the only ones who rely on literature reviews, recall the last time you went on Wikipedia . If you think about it, Wikipedia is really just a giant Literature Review on millions of topics. Although the information on Wikipedia is not formally peer-reviewed like the reviews published in academic journals, they do cite all their sources and frequently revise to keep the information current. Clearly there's a market for relevant information. If you really want your mind to explode Inception -style, look up "Wikipedia" on Wikipedia and you'll find a literature review about a literature review. Crazy.

All this is a long way of saying that literature reviews are a part of life. And they're a huge part of any scholarly discipline, any successful business, and even our basic human desire for knowledge. So if you're ready to learn how to tackle your own literature review, let's talk about the first steps in Chapter 11 How to Plan a Literature Review .

Brigham Young University

Cristie Cowles Charles teaches writing and literature courses at Brigham Young University in Provo, Utah. She enjoys sparking a love for writing in her students--or at least a love for having had written (it's always worth it in the end, right?). She thinks pumpkin pie counts as a vegetable, is married to a super hot mechanical engineering and neuroscience professor (yes, they exist), and adores her five magnificent children.

This content is provided to you freely by BYU Open Learning Network.

Access it online or download it at https://open.byu.edu/advancedwriting/literature_review .

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• What is a Book Review or Book Report?
• What is a Literature Review?

Also referred to as a book report, a  book review  consists of "critical comments on a book, especially when it is first published" ("Book Review, 2006). 

Similar to a short essay, a book review typically includes several of these elements:

     •  Description of the book's main topic, purpose and/or point of view, answering questions such as:

            •  What is the genre of the work (i.e. novel, non-fiction, memoir etc.)?

            •  Who is the intended audience?

            •  If a fictional work, what are the key themes, motifs, and/or plot devices?

            •  If a non-fictional work, what are the main arguments and ideas?

      •  Assessment of the book's main points, biases or flaws

      •  Critical analysis of the book's strengths and weaknesses, literary value and/or overall quality and contribution to the subject area

      •  If non-fiction, an explanation of how the book fits into the academic or popular discourse on a topic or subject area

Book Review. (2006). In P. Collin (Ed.),  Dictionary of publishing and printing . London, United Kingdom: A&C Black. Retrieved from http://search.credoreference.com

Follow these links to learn more about book reviews:

• Book Reviews - University of North Carolina at Chapel Hill
• How to Write Book Reviews - Queens University
• How to write a book report and a book review - Concordia University Libraries

A literature review is a "comprehensive study and interpretation of literature that addresses a specific topic" (Aveyard, 2010).

Literature reviews are generally conducted in one of two ways:

1) As a preliminary review before a larger study in order to critically evaluate the current literature and justify why further study and research is required.

In this case, the researcher must "systematically search, critique and combine the literature to demonstrate a gap in the existing research base" while demonstrating "their understanding of both the research and the methods previously used to investigate the area" (Aveyard, 2010).

2) As a project in itself that provides a comprehensive survey of the works published in a particular discipline or area of research over a specified period of time.

Sometimes referred to as a systematic literature review or meta-analysis, this type of literature review is a critical survey that attempts to "evaluate and interpret all available research evidence relevant to a particular question" (Glasziou, 2001).

Aveyard, H. (2010). Doing a literature review in health and social care: A practical guide (2nd ed.). Bershire, United Kingdom: Open University Press.

Galsziou, P. (2001). Systematic reviews in health care: A practical guide . New York, NY: Cambridge University Press.

Learn more about literature reviews:

• Guidelines for writing a literature review - University of Minnesota Duluth A step-by-step guide for writing a literature review
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CC0006 Basics of Report Writing

Structure of a report (case study, literature review or survey).

• Structure of report (Site visit)
• Citing Sources
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The information in the report has to be organised in the best possible way for the reader to understand the issue being investigated, analysis of the findings and recommendations or implications that relate directly to the findings. Given below are the main sections of a standard report. Click on each section heading to learn more about it.

• Tells the reader what the report is about
• Informative, short, catchy

Example - Sea level rise in Singapore : Causes, Impact and Solution

The title page must also include group name, group members and their matriculation numbers.

Content s Page

• Has headings and subheadings that show the reader where the various sections of the report are located
• Written on a separate page
• Includes the page numbers of each section
• Briefly summarises the report, the process of research and final conclusions
• Provides a quick overview of the report and describes the main highlights
• Short, usually not more than 150 words in length
• Mention briefly why you choose this project, what are the implications and what kind of problems it will solve

Usually, the abstract is written last, ie. after writing the other sections and you know the key points to draw out from these sections. Abstracts allow readers who may be interested in the report to decide whether it is relevant to their purposes.

Introduction

• Discusses the background and sets the context
• Introduces the topic, significance of the problem, and the purpose of research
• Gives the scope ie shows what it includes and excludes

In the introduction, write about what motivates your project, what makes it interesting, what questions do you aim to answer by doing your project. The introduction lays the foundation for understanding the research problem and should be written in a way that leads the reader from the general subject area of the topic to the particular topic of research.

Literature Review

• Helps to gain an understanding of the existing research in that topic
• To develop on your own ideas and build your ideas based on the existing knowledge
• Prevents duplication of the research done by others

Search the existing literature for information. Identify the data pertinent to your topic. Review, extract the relevant information for eg how the study was conducted and the findings. Summarise the information. Write what is already known about the topic and what do the sources that you have reviewed say. Identify conflicts in previous studies, open questions, or gaps that may exist. If you are doing

• Case study - look for background information and if any similar case studies have been done before.
• Literature review - find out from literature, what is the background to the questions that you are looking into
• Site visit - use the literature review to read up and prepare good questions before hand.
• Survey - find out if similar surveys have been done before and what did they find?

Keep a record of the source details of any information you want to use in your report so that you can reference them accurately.

Methodology

Methodology is the approach that you take to gather data and arrive at the recommendation(s). Choose a method that is appropriate for the research topic and explain it in detail.

In this section, address the following: a) How the data was collected b) How it was analysed and c) Explain or justify why a particular method was chosen.

Usually, the methodology is written in the past tense and can be in the passive voice. Some examples of the different methods that you can use to gather data are given below. The data collected provides evidence to build your arguments. Collect data, integrate the findings and perspectives from different studies and add your own analysis of its feasibility.

• Explore the literature/news/internet sources to know the topic in depth
• Give a description of how you selected the literature for your project
• Compare the studies, and highlight the findings, gaps or limitations.
• An in-depth, detailed examination of specific cases within a real-world context.
• Enables you to examine the data within a specific context.
• Examine a well defined case to identify the essential factors, process and relationship.
• Write the case description, the context and the process involved.
• Make sense of the evidence in the case(s) to answer the research question
• Gather data from a predefined group of respondents by asking relevant questions
• Can be conducted in person or online
• Why you chose this method (questionnaires, focus group, experimental procedure, etc)
• How you carried out the survey. Include techniques and any equipment you used
• If there were participants in your research, who were they? How did you select them and how may were there?
• How the survey questions address the different aspects of the research question
• Analyse the technology / policy approaches by visiting the required sites
• Make a detailed report on its features and your understanding of it

Results and Analysis

• Present the results of the study. You may consider visualising the results in tables and graphs, graphics etc.
• Analyse the results to obtain answer to the research question.
• Provide an analysis of the technical and financial feasibility, social acceptability etc

Discussion, Limitation(s) and Implication(s)

• Discuss your interpretations of the analysis and the significance of your findings
• Explain any new understanding or insights that emerged as a result of your research
• Consider the different perspectives (social, economic and environmental)in the discussion
• Explain the limitation(s)
• Explain how could what you found be used to make a difference for sustainability

Conclusion and Recommendations

• Summarise the significance and outcome of the study highlighting the key points.
• Come up with alternatives and propose specific actions based on the alternatives
• Describe the result or improvement it would achieve
• Explain how it will be implemented

Recommendations should have an innovative approach and should be feasible. It should make a significant difference in solving the issue under discussion.

• List the sources you have referred to in your writing
• Use the recommended citation style consistently in your report

Appendix (if necessary/any)

Include any material relating to the report and research that does not fit in the body of the report, in the appendix. For example, you may include survey questionnaire and results in the appendix.

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Lau F, Kuziemsky C, editors. Handbook of eHealth Evaluation: An Evidence-based Approach [Internet]. Victoria (BC): University of Victoria; 2017 Feb 27.

Handbook of eHealth Evaluation: An Evidence-based Approach [Internet].

Chapter 9 methods for literature reviews.

Guy Paré and Spyros Kitsiou .

9.1. Introduction

Literature reviews play a critical role in scholarship because science remains, first and foremost, a cumulative endeavour ( vom Brocke et al., 2009 ). As in any academic discipline, rigorous knowledge syntheses are becoming indispensable in keeping up with an exponentially growing eHealth literature, assisting practitioners, academics, and graduate students in finding, evaluating, and synthesizing the contents of many empirical and conceptual papers. Among other methods, literature reviews are essential for: (a) identifying what has been written on a subject or topic; (b) determining the extent to which a specific research area reveals any interpretable trends or patterns; (c) aggregating empirical findings related to a narrow research question to support evidence-based practice; (d) generating new frameworks and theories; and (e) identifying topics or questions requiring more investigation ( Paré, Trudel, Jaana, & Kitsiou, 2015 ).

Literature reviews can take two major forms. The most prevalent one is the “literature review” or “background” section within a journal paper or a chapter in a graduate thesis. This section synthesizes the extant literature and usually identifies the gaps in knowledge that the empirical study addresses ( Sylvester, Tate, & Johnstone, 2013 ). It may also provide a theoretical foundation for the proposed study, substantiate the presence of the research problem, justify the research as one that contributes something new to the cumulated knowledge, or validate the methods and approaches for the proposed study ( Hart, 1998 ; Levy & Ellis, 2006 ).

The second form of literature review, which is the focus of this chapter, constitutes an original and valuable work of research in and of itself ( Paré et al., 2015 ). Rather than providing a base for a researcher’s own work, it creates a solid starting point for all members of the community interested in a particular area or topic ( Mulrow, 1987 ). The so-called “review article” is a journal-length paper which has an overarching purpose to synthesize the literature in a field, without collecting or analyzing any primary data ( Green, Johnson, & Adams, 2006 ).

When appropriately conducted, review articles represent powerful information sources for practitioners looking for state-of-the art evidence to guide their decision-making and work practices ( Paré et al., 2015 ). Further, high-quality reviews become frequently cited pieces of work which researchers seek out as a first clear outline of the literature when undertaking empirical studies ( Cooper, 1988 ; Rowe, 2014 ). Scholars who track and gauge the impact of articles have found that review papers are cited and downloaded more often than any other type of published article ( Cronin, Ryan, & Coughlan, 2008 ; Montori, Wilczynski, Morgan, Haynes, & Hedges, 2003 ; Patsopoulos, Analatos, & Ioannidis, 2005 ). The reason for their popularity may be the fact that reading the review enables one to have an overview, if not a detailed knowledge of the area in question, as well as references to the most useful primary sources ( Cronin et al., 2008 ). Although they are not easy to conduct, the commitment to complete a review article provides a tremendous service to one’s academic community ( Paré et al., 2015 ; Petticrew & Roberts, 2006 ). Most, if not all, peer-reviewed journals in the fields of medical informatics publish review articles of some type.

The main objectives of this chapter are fourfold: (a) to provide an overview of the major steps and activities involved in conducting a stand-alone literature review; (b) to describe and contrast the different types of review articles that can contribute to the eHealth knowledge base; (c) to illustrate each review type with one or two examples from the eHealth literature; and (d) to provide a series of recommendations for prospective authors of review articles in this domain.

9.2. Overview of the Literature Review Process and Steps

As explained in Templier and Paré (2015) , there are six generic steps involved in conducting a review article:

• formulating the research question(s) and objective(s),
• searching the extant literature,
• screening for inclusion,
• assessing the quality of primary studies,
• extracting data, and
• analyzing data.

Although these steps are presented here in sequential order, one must keep in mind that the review process can be iterative and that many activities can be initiated during the planning stage and later refined during subsequent phases ( Finfgeld-Connett & Johnson, 2013 ; Kitchenham & Charters, 2007 ).

Formulating the research question(s) and objective(s): As a first step, members of the review team must appropriately justify the need for the review itself ( Petticrew & Roberts, 2006 ), identify the review’s main objective(s) ( Okoli & Schabram, 2010 ), and define the concepts or variables at the heart of their synthesis ( Cooper & Hedges, 2009 ; Webster & Watson, 2002 ). Importantly, they also need to articulate the research question(s) they propose to investigate ( Kitchenham & Charters, 2007 ). In this regard, we concur with Jesson, Matheson, and Lacey (2011) that clearly articulated research questions are key ingredients that guide the entire review methodology; they underscore the type of information that is needed, inform the search for and selection of relevant literature, and guide or orient the subsequent analysis. Searching the extant literature: The next step consists of searching the literature and making decisions about the suitability of material to be considered in the review ( Cooper, 1988 ). There exist three main coverage strategies. First, exhaustive coverage means an effort is made to be as comprehensive as possible in order to ensure that all relevant studies, published and unpublished, are included in the review and, thus, conclusions are based on this all-inclusive knowledge base. The second type of coverage consists of presenting materials that are representative of most other works in a given field or area. Often authors who adopt this strategy will search for relevant articles in a small number of top-tier journals in a field ( Paré et al., 2015 ). In the third strategy, the review team concentrates on prior works that have been central or pivotal to a particular topic. This may include empirical studies or conceptual papers that initiated a line of investigation, changed how problems or questions were framed, introduced new methods or concepts, or engendered important debate ( Cooper, 1988 ). Screening for inclusion: The following step consists of evaluating the applicability of the material identified in the preceding step ( Levy & Ellis, 2006 ; vom Brocke et al., 2009 ). Once a group of potential studies has been identified, members of the review team must screen them to determine their relevance ( Petticrew & Roberts, 2006 ). A set of predetermined rules provides a basis for including or excluding certain studies. This exercise requires a significant investment on the part of researchers, who must ensure enhanced objectivity and avoid biases or mistakes. As discussed later in this chapter, for certain types of reviews there must be at least two independent reviewers involved in the screening process and a procedure to resolve disagreements must also be in place ( Liberati et al., 2009 ; Shea et al., 2009 ). Assessing the quality of primary studies: In addition to screening material for inclusion, members of the review team may need to assess the scientific quality of the selected studies, that is, appraise the rigour of the research design and methods. Such formal assessment, which is usually conducted independently by at least two coders, helps members of the review team refine which studies to include in the final sample, determine whether or not the differences in quality may affect their conclusions, or guide how they analyze the data and interpret the findings ( Petticrew & Roberts, 2006 ). Ascribing quality scores to each primary study or considering through domain-based evaluations which study components have or have not been designed and executed appropriately makes it possible to reflect on the extent to which the selected study addresses possible biases and maximizes validity ( Shea et al., 2009 ). Extracting data: The following step involves gathering or extracting applicable information from each primary study included in the sample and deciding what is relevant to the problem of interest ( Cooper & Hedges, 2009 ). Indeed, the type of data that should be recorded mainly depends on the initial research questions ( Okoli & Schabram, 2010 ). However, important information may also be gathered about how, when, where and by whom the primary study was conducted, the research design and methods, or qualitative/quantitative results ( Cooper & Hedges, 2009 ). Analyzing and synthesizing data : As a final step, members of the review team must collate, summarize, aggregate, organize, and compare the evidence extracted from the included studies. The extracted data must be presented in a meaningful way that suggests a new contribution to the extant literature ( Jesson et al., 2011 ). Webster and Watson (2002) warn researchers that literature reviews should be much more than lists of papers and should provide a coherent lens to make sense of extant knowledge on a given topic. There exist several methods and techniques for synthesizing quantitative (e.g., frequency analysis, meta-analysis) and qualitative (e.g., grounded theory, narrative analysis, meta-ethnography) evidence ( Dixon-Woods, Agarwal, Jones, Young, & Sutton, 2005 ; Thomas & Harden, 2008 ).

9.3. Types of Review Articles and Brief Illustrations

EHealth researchers have at their disposal a number of approaches and methods for making sense out of existing literature, all with the purpose of casting current research findings into historical contexts or explaining contradictions that might exist among a set of primary research studies conducted on a particular topic. Our classification scheme is largely inspired from Paré and colleagues’ (2015) typology. Below we present and illustrate those review types that we feel are central to the growth and development of the eHealth domain.

9.3.1. Narrative Reviews

The narrative review is the “traditional” way of reviewing the extant literature and is skewed towards a qualitative interpretation of prior knowledge ( Sylvester et al., 2013 ). Put simply, a narrative review attempts to summarize or synthesize what has been written on a particular topic but does not seek generalization or cumulative knowledge from what is reviewed ( Davies, 2000 ; Green et al., 2006 ). Instead, the review team often undertakes the task of accumulating and synthesizing the literature to demonstrate the value of a particular point of view ( Baumeister & Leary, 1997 ). As such, reviewers may selectively ignore or limit the attention paid to certain studies in order to make a point. In this rather unsystematic approach, the selection of information from primary articles is subjective, lacks explicit criteria for inclusion and can lead to biased interpretations or inferences ( Green et al., 2006 ). There are several narrative reviews in the particular eHealth domain, as in all fields, which follow such an unstructured approach ( Silva et al., 2015 ; Paul et al., 2015 ).

Despite these criticisms, this type of review can be very useful in gathering together a volume of literature in a specific subject area and synthesizing it. As mentioned above, its primary purpose is to provide the reader with a comprehensive background for understanding current knowledge and highlighting the significance of new research ( Cronin et al., 2008 ). Faculty like to use narrative reviews in the classroom because they are often more up to date than textbooks, provide a single source for students to reference, and expose students to peer-reviewed literature ( Green et al., 2006 ). For researchers, narrative reviews can inspire research ideas by identifying gaps or inconsistencies in a body of knowledge, thus helping researchers to determine research questions or formulate hypotheses. Importantly, narrative reviews can also be used as educational articles to bring practitioners up to date with certain topics of issues ( Green et al., 2006 ).

Recently, there have been several efforts to introduce more rigour in narrative reviews that will elucidate common pitfalls and bring changes into their publication standards. Information systems researchers, among others, have contributed to advancing knowledge on how to structure a “traditional” review. For instance, Levy and Ellis (2006) proposed a generic framework for conducting such reviews. Their model follows the systematic data processing approach comprised of three steps, namely: (a) literature search and screening; (b) data extraction and analysis; and (c) writing the literature review. They provide detailed and very helpful instructions on how to conduct each step of the review process. As another methodological contribution, vom Brocke et al. (2009) offered a series of guidelines for conducting literature reviews, with a particular focus on how to search and extract the relevant body of knowledge. Last, Bandara, Miskon, and Fielt (2011) proposed a structured, predefined and tool-supported method to identify primary studies within a feasible scope, extract relevant content from identified articles, synthesize and analyze the findings, and effectively write and present the results of the literature review. We highly recommend that prospective authors of narrative reviews consult these useful sources before embarking on their work.

Darlow and Wen (2015) provide a good example of a highly structured narrative review in the eHealth field. These authors synthesized published articles that describe the development process of mobile health ( m-health ) interventions for patients’ cancer care self-management. As in most narrative reviews, the scope of the research questions being investigated is broad: (a) how development of these systems are carried out; (b) which methods are used to investigate these systems; and (c) what conclusions can be drawn as a result of the development of these systems. To provide clear answers to these questions, a literature search was conducted on six electronic databases and Google Scholar . The search was performed using several terms and free text words, combining them in an appropriate manner. Four inclusion and three exclusion criteria were utilized during the screening process. Both authors independently reviewed each of the identified articles to determine eligibility and extract study information. A flow diagram shows the number of studies identified, screened, and included or excluded at each stage of study selection. In terms of contributions, this review provides a series of practical recommendations for m-health intervention development.

9.3.2. Descriptive or Mapping Reviews

The primary goal of a descriptive review is to determine the extent to which a body of knowledge in a particular research topic reveals any interpretable pattern or trend with respect to pre-existing propositions, theories, methodologies or findings ( King & He, 2005 ; Paré et al., 2015 ). In contrast with narrative reviews, descriptive reviews follow a systematic and transparent procedure, including searching, screening and classifying studies ( Petersen, Vakkalanka, & Kuzniarz, 2015 ). Indeed, structured search methods are used to form a representative sample of a larger group of published works ( Paré et al., 2015 ). Further, authors of descriptive reviews extract from each study certain characteristics of interest, such as publication year, research methods, data collection techniques, and direction or strength of research outcomes (e.g., positive, negative, or non-significant) in the form of frequency analysis to produce quantitative results ( Sylvester et al., 2013 ). In essence, each study included in a descriptive review is treated as the unit of analysis and the published literature as a whole provides a database from which the authors attempt to identify any interpretable trends or draw overall conclusions about the merits of existing conceptualizations, propositions, methods or findings ( Paré et al., 2015 ). In doing so, a descriptive review may claim that its findings represent the state of the art in a particular domain ( King & He, 2005 ).

In the fields of health sciences and medical informatics, reviews that focus on examining the range, nature and evolution of a topic area are described by Anderson, Allen, Peckham, and Goodwin (2008) as mapping reviews . Like descriptive reviews, the research questions are generic and usually relate to publication patterns and trends. There is no preconceived plan to systematically review all of the literature although this can be done. Instead, researchers often present studies that are representative of most works published in a particular area and they consider a specific time frame to be mapped.

An example of this approach in the eHealth domain is offered by DeShazo, Lavallie, and Wolf (2009). The purpose of this descriptive or mapping review was to characterize publication trends in the medical informatics literature over a 20-year period (1987 to 2006). To achieve this ambitious objective, the authors performed a bibliometric analysis of medical informatics citations indexed in medline using publication trends, journal frequencies, impact factors, Medical Subject Headings (MeSH) term frequencies, and characteristics of citations. Findings revealed that there were over 77,000 medical informatics articles published during the covered period in numerous journals and that the average annual growth rate was 12%. The MeSH term analysis also suggested a strong interdisciplinary trend. Finally, average impact scores increased over time with two notable growth periods. Overall, patterns in research outputs that seem to characterize the historic trends and current components of the field of medical informatics suggest it may be a maturing discipline (DeShazo et al., 2009).

9.3.3. Scoping Reviews

Scoping reviews attempt to provide an initial indication of the potential size and nature of the extant literature on an emergent topic (Arksey & O’Malley, 2005; Daudt, van Mossel, & Scott, 2013 ; Levac, Colquhoun, & O’Brien, 2010). A scoping review may be conducted to examine the extent, range and nature of research activities in a particular area, determine the value of undertaking a full systematic review (discussed next), or identify research gaps in the extant literature ( Paré et al., 2015 ). In line with their main objective, scoping reviews usually conclude with the presentation of a detailed research agenda for future works along with potential implications for both practice and research.

Unlike narrative and descriptive reviews, the whole point of scoping the field is to be as comprehensive as possible, including grey literature (Arksey & O’Malley, 2005). Inclusion and exclusion criteria must be established to help researchers eliminate studies that are not aligned with the research questions. It is also recommended that at least two independent coders review abstracts yielded from the search strategy and then the full articles for study selection ( Daudt et al., 2013 ). The synthesized evidence from content or thematic analysis is relatively easy to present in tabular form (Arksey & O’Malley, 2005; Thomas & Harden, 2008 ).

One of the most highly cited scoping reviews in the eHealth domain was published by Archer, Fevrier-Thomas, Lokker, McKibbon, and Straus (2011) . These authors reviewed the existing literature on personal health record ( phr ) systems including design, functionality, implementation, applications, outcomes, and benefits. Seven databases were searched from 1985 to March 2010. Several search terms relating to phr s were used during this process. Two authors independently screened titles and abstracts to determine inclusion status. A second screen of full-text articles, again by two independent members of the research team, ensured that the studies described phr s. All in all, 130 articles met the criteria and their data were extracted manually into a database. The authors concluded that although there is a large amount of survey, observational, cohort/panel, and anecdotal evidence of phr benefits and satisfaction for patients, more research is needed to evaluate the results of phr implementations. Their in-depth analysis of the literature signalled that there is little solid evidence from randomized controlled trials or other studies through the use of phr s. Hence, they suggested that more research is needed that addresses the current lack of understanding of optimal functionality and usability of these systems, and how they can play a beneficial role in supporting patient self-management ( Archer et al., 2011 ).

9.3.4. Forms of Aggregative Reviews

Healthcare providers, practitioners, and policy-makers are nowadays overwhelmed with large volumes of information, including research-based evidence from numerous clinical trials and evaluation studies, assessing the effectiveness of health information technologies and interventions ( Ammenwerth & de Keizer, 2004 ; Deshazo et al., 2009 ). It is unrealistic to expect that all these disparate actors will have the time, skills, and necessary resources to identify the available evidence in the area of their expertise and consider it when making decisions. Systematic reviews that involve the rigorous application of scientific strategies aimed at limiting subjectivity and bias (i.e., systematic and random errors) can respond to this challenge.

Systematic reviews attempt to aggregate, appraise, and synthesize in a single source all empirical evidence that meet a set of previously specified eligibility criteria in order to answer a clearly formulated and often narrow research question on a particular topic of interest to support evidence-based practice ( Liberati et al., 2009 ). They adhere closely to explicit scientific principles ( Liberati et al., 2009 ) and rigorous methodological guidelines (Higgins & Green, 2008) aimed at reducing random and systematic errors that can lead to deviations from the truth in results or inferences. The use of explicit methods allows systematic reviews to aggregate a large body of research evidence, assess whether effects or relationships are in the same direction and of the same general magnitude, explain possible inconsistencies between study results, and determine the strength of the overall evidence for every outcome of interest based on the quality of included studies and the general consistency among them ( Cook, Mulrow, & Haynes, 1997 ). The main procedures of a systematic review involve:

• Formulating a review question and developing a search strategy based on explicit inclusion criteria for the identification of eligible studies (usually described in the context of a detailed review protocol).
• Searching for eligible studies using multiple databases and information sources, including grey literature sources, without any language restrictions.
• Selecting studies, extracting data, and assessing risk of bias in a duplicate manner using two independent reviewers to avoid random or systematic errors in the process.
• Analyzing data using quantitative or qualitative methods.
• Presenting results in summary of findings tables.
• Interpreting results and drawing conclusions.

Many systematic reviews, but not all, use statistical methods to combine the results of independent studies into a single quantitative estimate or summary effect size. Known as meta-analyses , these reviews use specific data extraction and statistical techniques (e.g., network, frequentist, or Bayesian meta-analyses) to calculate from each study by outcome of interest an effect size along with a confidence interval that reflects the degree of uncertainty behind the point estimate of effect ( Borenstein, Hedges, Higgins, & Rothstein, 2009 ; Deeks, Higgins, & Altman, 2008 ). Subsequently, they use fixed or random-effects analysis models to combine the results of the included studies, assess statistical heterogeneity, and calculate a weighted average of the effect estimates from the different studies, taking into account their sample sizes. The summary effect size is a value that reflects the average magnitude of the intervention effect for a particular outcome of interest or, more generally, the strength of a relationship between two variables across all studies included in the systematic review. By statistically combining data from multiple studies, meta-analyses can create more precise and reliable estimates of intervention effects than those derived from individual studies alone, when these are examined independently as discrete sources of information.

The review by Gurol-Urganci, de Jongh, Vodopivec-Jamsek, Atun, and Car (2013) on the effects of mobile phone messaging reminders for attendance at healthcare appointments is an illustrative example of a high-quality systematic review with meta-analysis. Missed appointments are a major cause of inefficiency in healthcare delivery with substantial monetary costs to health systems. These authors sought to assess whether mobile phone-based appointment reminders delivered through Short Message Service ( sms ) or Multimedia Messaging Service ( mms ) are effective in improving rates of patient attendance and reducing overall costs. To this end, they conducted a comprehensive search on multiple databases using highly sensitive search strategies without language or publication-type restrictions to identify all rct s that are eligible for inclusion. In order to minimize the risk of omitting eligible studies not captured by the original search, they supplemented all electronic searches with manual screening of trial registers and references contained in the included studies. Study selection, data extraction, and risk of bias assessments were performed inde­­pen­dently by two coders using standardized methods to ensure consistency and to eliminate potential errors. Findings from eight rct s involving 6,615 participants were pooled into meta-analyses to calculate the magnitude of effects that mobile text message reminders have on the rate of attendance at healthcare appointments compared to no reminders and phone call reminders.

Meta-analyses are regarded as powerful tools for deriving meaningful conclusions. However, there are situations in which it is neither reasonable nor appropriate to pool studies together using meta-analytic methods simply because there is extensive clinical heterogeneity between the included studies or variation in measurement tools, comparisons, or outcomes of interest. In these cases, systematic reviews can use qualitative synthesis methods such as vote counting, content analysis, classification schemes and tabulations, as an alternative approach to narratively synthesize the results of the independent studies included in the review. This form of review is known as qualitative systematic review.

A rigorous example of one such review in the eHealth domain is presented by Mickan, Atherton, Roberts, Heneghan, and Tilson (2014) on the use of handheld computers by healthcare professionals and their impact on access to information and clinical decision-making. In line with the methodological guide­lines for systematic reviews, these authors: (a) developed and registered with prospero ( www.crd.york.ac.uk/ prospero / ) an a priori review protocol; (b) conducted comprehensive searches for eligible studies using multiple databases and other supplementary strategies (e.g., forward searches); and (c) subsequently carried out study selection, data extraction, and risk of bias assessments in a duplicate manner to eliminate potential errors in the review process. Heterogeneity between the included studies in terms of reported outcomes and measures precluded the use of meta-analytic methods. To this end, the authors resorted to using narrative analysis and synthesis to describe the effectiveness of handheld computers on accessing information for clinical knowledge, adherence to safety and clinical quality guidelines, and diagnostic decision-making.

In recent years, the number of systematic reviews in the field of health informatics has increased considerably. Systematic reviews with discordant findings can cause great confusion and make it difficult for decision-makers to interpret the review-level evidence ( Moher, 2013 ). Therefore, there is a growing need for appraisal and synthesis of prior systematic reviews to ensure that decision-making is constantly informed by the best available accumulated evidence. Umbrella reviews , also known as overviews of systematic reviews, are tertiary types of evidence synthesis that aim to accomplish this; that is, they aim to compare and contrast findings from multiple systematic reviews and meta-analyses ( Becker & Oxman, 2008 ). Umbrella reviews generally adhere to the same principles and rigorous methodological guidelines used in systematic reviews. However, the unit of analysis in umbrella reviews is the systematic review rather than the primary study ( Becker & Oxman, 2008 ). Unlike systematic reviews that have a narrow focus of inquiry, umbrella reviews focus on broader research topics for which there are several potential interventions ( Smith, Devane, Begley, & Clarke, 2011 ). A recent umbrella review on the effects of home telemonitoring interventions for patients with heart failure critically appraised, compared, and synthesized evidence from 15 systematic reviews to investigate which types of home telemonitoring technologies and forms of interventions are more effective in reducing mortality and hospital admissions ( Kitsiou, Paré, & Jaana, 2015 ).

9.3.5. Realist Reviews

Realist reviews are theory-driven interpretative reviews developed to inform, enhance, or supplement conventional systematic reviews by making sense of heterogeneous evidence about complex interventions applied in diverse contexts in a way that informs policy decision-making ( Greenhalgh, Wong, Westhorp, & Pawson, 2011 ). They originated from criticisms of positivist systematic reviews which centre on their “simplistic” underlying assumptions ( Oates, 2011 ). As explained above, systematic reviews seek to identify causation. Such logic is appropriate for fields like medicine and education where findings of randomized controlled trials can be aggregated to see whether a new treatment or intervention does improve outcomes. However, many argue that it is not possible to establish such direct causal links between interventions and outcomes in fields such as social policy, management, and information systems where for any intervention there is unlikely to be a regular or consistent outcome ( Oates, 2011 ; Pawson, 2006 ; Rousseau, Manning, & Denyer, 2008 ).

To circumvent these limitations, Pawson, Greenhalgh, Harvey, and Walshe (2005) have proposed a new approach for synthesizing knowledge that seeks to unpack the mechanism of how “complex interventions” work in particular contexts. The basic research question — what works? — which is usually associated with systematic reviews changes to: what is it about this intervention that works, for whom, in what circumstances, in what respects and why? Realist reviews have no particular preference for either quantitative or qualitative evidence. As a theory-building approach, a realist review usually starts by articulating likely underlying mechanisms and then scrutinizes available evidence to find out whether and where these mechanisms are applicable ( Shepperd et al., 2009 ). Primary studies found in the extant literature are viewed as case studies which can test and modify the initial theories ( Rousseau et al., 2008 ).

The main objective pursued in the realist review conducted by Otte-Trojel, de Bont, Rundall, and van de Klundert (2014) was to examine how patient portals contribute to health service delivery and patient outcomes. The specific goals were to investigate how outcomes are produced and, most importantly, how variations in outcomes can be explained. The research team started with an exploratory review of background documents and research studies to identify ways in which patient portals may contribute to health service delivery and patient outcomes. The authors identified six main ways which represent “educated guesses” to be tested against the data in the evaluation studies. These studies were identified through a formal and systematic search in four databases between 2003 and 2013. Two members of the research team selected the articles using a pre-established list of inclusion and exclusion criteria and following a two-step procedure. The authors then extracted data from the selected articles and created several tables, one for each outcome category. They organized information to bring forward those mechanisms where patient portals contribute to outcomes and the variation in outcomes across different contexts.

9.3.6. Critical Reviews

Lastly, critical reviews aim to provide a critical evaluation and interpretive analysis of existing literature on a particular topic of interest to reveal strengths, weaknesses, contradictions, controversies, inconsistencies, and/or other important issues with respect to theories, hypotheses, research methods or results ( Baumeister & Leary, 1997 ; Kirkevold, 1997 ). Unlike other review types, critical reviews attempt to take a reflective account of the research that has been done in a particular area of interest, and assess its credibility by using appraisal instruments or critical interpretive methods. In this way, critical reviews attempt to constructively inform other scholars about the weaknesses of prior research and strengthen knowledge development by giving focus and direction to studies for further improvement ( Kirkevold, 1997 ).

Kitsiou, Paré, and Jaana (2013) provide an example of a critical review that assessed the methodological quality of prior systematic reviews of home telemonitoring studies for chronic patients. The authors conducted a comprehensive search on multiple databases to identify eligible reviews and subsequently used a validated instrument to conduct an in-depth quality appraisal. Results indicate that the majority of systematic reviews in this particular area suffer from important methodological flaws and biases that impair their internal validity and limit their usefulness for clinical and decision-making purposes. To this end, they provide a number of recommendations to strengthen knowledge development towards improving the design and execution of future reviews on home telemonitoring.

9.4. Summary

Table 9.1 outlines the main types of literature reviews that were described in the previous sub-sections and summarizes the main characteristics that distinguish one review type from another. It also includes key references to methodological guidelines and useful sources that can be used by eHealth scholars and researchers for planning and developing reviews.

Typology of Literature Reviews (adapted from Paré et al., 2015).

As shown in Table 9.1 , each review type addresses different kinds of research questions or objectives, which subsequently define and dictate the methods and approaches that need to be used to achieve the overarching goal(s) of the review. For example, in the case of narrative reviews, there is greater flexibility in searching and synthesizing articles ( Green et al., 2006 ). Researchers are often relatively free to use a diversity of approaches to search, identify, and select relevant scientific articles, describe their operational characteristics, present how the individual studies fit together, and formulate conclusions. On the other hand, systematic reviews are characterized by their high level of systematicity, rigour, and use of explicit methods, based on an “a priori” review plan that aims to minimize bias in the analysis and synthesis process (Higgins & Green, 2008). Some reviews are exploratory in nature (e.g., scoping/mapping reviews), whereas others may be conducted to discover patterns (e.g., descriptive reviews) or involve a synthesis approach that may include the critical analysis of prior research ( Paré et al., 2015 ). Hence, in order to select the most appropriate type of review, it is critical to know before embarking on a review project, why the research synthesis is conducted and what type of methods are best aligned with the pursued goals.

9.5. Concluding Remarks

In light of the increased use of evidence-based practice and research generating stronger evidence ( Grady et al., 2011 ; Lyden et al., 2013 ), review articles have become essential tools for summarizing, synthesizing, integrating or critically appraising prior knowledge in the eHealth field. As mentioned earlier, when rigorously conducted review articles represent powerful information sources for eHealth scholars and practitioners looking for state-of-the-art evidence. The typology of literature reviews we used herein will allow eHealth researchers, graduate students and practitioners to gain a better understanding of the similarities and differences between review types.

We must stress that this classification scheme does not privilege any specific type of review as being of higher quality than another ( Paré et al., 2015 ). As explained above, each type of review has its own strengths and limitations. Having said that, we realize that the methodological rigour of any review — be it qualitative, quantitative or mixed — is a critical aspect that should be considered seriously by prospective authors. In the present context, the notion of rigour refers to the reliability and validity of the review process described in section 9.2. For one thing, reliability is related to the reproducibility of the review process and steps, which is facilitated by a comprehensive documentation of the literature search process, extraction, coding and analysis performed in the review. Whether the search is comprehensive or not, whether it involves a methodical approach for data extraction and synthesis or not, it is important that the review documents in an explicit and transparent manner the steps and approach that were used in the process of its development. Next, validity characterizes the degree to which the review process was conducted appropriately. It goes beyond documentation and reflects decisions related to the selection of the sources, the search terms used, the period of time covered, the articles selected in the search, and the application of backward and forward searches ( vom Brocke et al., 2009 ). In short, the rigour of any review article is reflected by the explicitness of its methods (i.e., transparency) and the soundness of the approach used. We refer those interested in the concepts of rigour and quality to the work of Templier and Paré (2015) which offers a detailed set of methodological guidelines for conducting and evaluating various types of review articles.

To conclude, our main objective in this chapter was to demystify the various types of literature reviews that are central to the continuous development of the eHealth field. It is our hope that our descriptive account will serve as a valuable source for those conducting, evaluating or using reviews in this important and growing domain.

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• Cite this Page Paré G, Kitsiou S. Chapter 9 Methods for Literature Reviews. In: Lau F, Kuziemsky C, editors. Handbook of eHealth Evaluation: An Evidence-based Approach [Internet]. Victoria (BC): University of Victoria; 2017 Feb 27.
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• Types of Review Articles and Brief Illustrations
• Concluding Remarks

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Annotated Bibliography vs. Literature Review

What's the big deal.

There are fundamental differences between an annotated bibliography and a literature review that are crucial to completing the assignment correctly. The chart below is provides an overview of the biggest differences between the two types of assignments in a side-by-side comparison. However, if you need more specific information about either assignment, visit our Annotated Bibliography and/or Literature Review pages for more detailed information on how to complete them. 

Differences between an annotated bibliography and literature review

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Case report article, a 26-year-old man with multiple organ failure caused by aeromonas dhakensis infection: a case report and literature review.

• 1 Department of Respiratory and Critical Care Medicine, People’s Hospital of Chongqing Liang Jiang New Area, Chongqing, China
• 2 Department of Respiratory and Critical Care Medicine, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China

Background: Infections in humans are mainly caused by Aeromonas hydrophila , Aeromonas caviae , and Aeromonas veronii . In recent years, Aeromonas dhakensis has been recognized as widely distributed in the environment, with strong virulence. However, this bacterial infection usually does not appear in patients with pneumonia as the first symptom.

Case report: We report a 26-year-old man who was admitted to the hospital with community-acquired pneumonia as the first symptom and developed serious conditions such as hemolytic uremic syndrome, multiple organ dysfunction, and hemorrhagic shock within a short period. He died after 13 h of admission, and the subsequent metagenomic-next generation sequencing test confirmed the finally identified pathogen of infection as A. dhakensis .

Conclusion: Aeromonas is a rare pathogen identified in the diagnosis of community-acquired pneumonia. Hence, doctors need to develop their experience in identifying the difference between infections caused by pathogenic microorganisms. Medical attention is essential during the occurrence of respiratory symptoms that could be controlled by empirical drugs, such as cephalosporins or quinolones. When patients with community-acquired pneumonia present hemoptysis and multiple organ dysfunction in clinical treatment, an unusual pathogen infection should be considered, and the underlying etiology should be clarified at the earliest for timely treatment.

Graphical Abstract.

Introduction

Aeromonas dhakensis is a Gram-negative bacillus that is widely distributed in water environments. The mortality rate caused by infection with A. dhakensis is higher than that of other Aeromonas infections due to the abundance of virulence genes. It causes gastroenteritis, wound infection, sepsis, respiratory tract infection, hepatobiliary disease, urinary tract infection, muscle necrosis, rhabdomyolysis, necrotizing fasciitis, and the rare

hemolytic uremic syndrome. If an acute infection is not treated promptly, it may develop rapidly and lead to serious consequences. In this case study, we reported the onset and treatment of a 26-year-old patient infected with A. dhakensis .

Case report

A 26-year-old man with no history of lung diseases or other disorders was admitted to the local hospital due to cough and fatigue for 3 days, hemoptysis, dyspnea, fever, chest pain, and wheezing for a day. The patient was admitted to our emergency department. A blood routine examination showed that the white blood cell count was 7.06 × 10 9 /L, and the percentage of neutrophils was 69.9%. The liver function showed alanine aminotransferase at 150 U/L and aspartate transferase at 84 U/L, and the kidney function-related creatinine level was 197 mmol/L, and the uric acid level was 607 mmol/L. The coagulation function D-dimer level was 3730 ng/mL. Blood gas analysis (without oxygen) revealed the following: pH 7.32, PCO 2 43 mmHg, PO 2 37 mmHg, BE −3.9 mmol/L, HCO 3 22.21 mmol/L, Lac 4.8 mmol/L, SO 2 65%, Na + 132 mmol/L, K + 3.8 mmol/L, and Glu tendency of 7.1 mmol/L. The Chest computer tomography (CT) scan displayed a double lung infection ( Figure 1 ). A physical examination revealed a body temperature of 37.5°C, and vital signs were within normal range. Lucid, poor spirit, and wet rales could be heard in both lungs. After 2 h, the patient was transferred to the Respiratory Intensive Care Unit (RICU).

Figure 1. (a–h) The chest computer tomography (CT) scan displayed a double lung infection.

According to the examination, the patient was diagnosed with severe pneumonia and abnormal liver function. While being kept on a non-invasive ventilator, 1,000 mg of imipenem was given intravenously every 8 h, 600 mg of linezolid was given intravenously every 6 h, and reduced glutathione, polyene phosphatidylcholine, and carlo sulfonyl sodium were used. After transferring the patient to RICU post 2 h, the hemoptysis level increased to almost 100 ml, and blood gas analysis indicated respiratory failure. Thus, the patient received endotracheal intubation. Then, tracheoscopy was performed and active hemorrhage was observed in the right upper lobe opening. The lavage fluid was collected and cultured. The right upper lobe bronchus was blocked by a bronchoscope balloon, pituitrin, carlo sulfonyl sodium, and hemagglutinin to stop the bleeding.

Typically, the bleeding could be controlled, but it was counterproductive. The blood was drained from the stomach tube, the urine turned to a soy sauce color, and blood pressure dropped. Considering the patient had gastrointestinal bleeding and hemolysis, emergency blood transfusion measures were initiated, and vasoactive drugs were administered. To date, 1,000 ml of blood was aspirated under a bronchoscope, 300 ml from a gastric tube, and 150 ml was drained by the urinary tube, and the patient went into hemorrhagic shock. In addition, antishock treatment and extracorporeal membrane oxygenation (ECMO) were considered.

These measures stabilized the patient’s blood pressure at 80–95/50–55 mmHg, and the oxygen saturation was stabilized at 80%–90%. Indubitably, the patient’s condition deteriorated rapidly, leading to multiple organ failures before the initiation of ECMO therapy and eventually leading to death. At 6.3 h after death, the blood cultures suggested the presence of Aeromonas hydrophila/Aeromonas caviae ( Figure 2 ). At 33 h, irrigation fluid culture also signaled the presence of A. hydrophila/A. caviae after the patient’s death. This is the first case of Aeromonas infection that we have encountered and also a rare case of multiple organ failure reported in the literature.

Figure 2. (a) Gram-negative bacilli were observed under an oil immersion lens. (b) Gram-negative bacilli were observed under an oil immersion lens. (c) Gram-negative bacilli were observed under a microscope. (d) Medium colony.

Aeromonas is a Gram-negative bacillus widely distributed in freshwater, river/estuarine water (brackish water), surface water, drinking water, polluted water bodies, and sewage sludge ( 1 – 5 ). The classification includes A. hydrophila , A. caviae, Aeromonas veronii biovar sobria, Aeromonas milmiliae, Aeromonas salmonicides, Aeromonas intermedialis, Aeromonas janeii, Aeromonas shuiensis , and Aeromonas fragilis ( 6 ). Human infections are commonly caused by A. hydrophila , A. veronii biovar sobria , and A. caviae ( 7 ). The most common route of infection is contact with fresh or brackish water, which is usually stagnant in warm months (May–October in the Northern Hemisphere), its bacterial count reaches a peak value, thereby elevating the incidence of Aeromonas infection in summer ( 8 , 9 ). Patients with chronic underlying diseases, such as nephritis, diabetes, tumors, leukemia, and hepatobiliary pancreas, have low immunity and are at a high risk of Aeromonas infection. It directly enters the blood through the peritoneal barrier and reaches the thoracic tissue, pelvic tissue, lymph, gallbladder, and other parts. In severe cases, it may be life-threatening ( 10 ). The patient, in this case, was a 26-year-old man with no underlying diseases or low immunity. However, he had embarked on self-driving trips for 3 days before the onset of the disease. En route, he swam in a lake, which could be the cause of Aeromonas infection; the onset was rapid, and the clinical manifestations were critical.

Aeromonas cause a variety of human diseases such as diarrhea, wound infection, bacteremia, respiratory tract infection, eye infection, osteomyelitis, meningitis, pelvic abscess, otitis, cystitis, endocarditis, peritonitis, cholecystitis, joint infection, necrotizing fasciitis, and folliculitis ( 11 – 16 ). Diarrhea is the most common clinical manifestation. Different from the typical infection symptoms, this patient had respiratory symptoms of cough, expectoration, and hemoptysis as initial presentation, without diarrhea.

Within 11 h of admission, 1,000 ml of blood was aspirated under a bronchoscope, 300 ml of blood from the gastric tube, and 150 ml of blood was drained by the urinary tube. Subsequently, Aeromonas was detected in blood culture and bronchoscopic lavage fluid culture, and the biochemical results are shown in Table 1 . The results indicated that the patient was infected with Aeromona s, leading to Aeromonas hemolytic-uremic syndrome, which is a rare manifestation caused by this bacterium. Since A. hydrophila/A. caviae is often confused with A. dhakensis due to similar homology, conventional automatic laboratory biochemical identification cannot distinguish the species type effectively ( 17 ). Hence, metagenomic-next generation sequencing was recommended for species identification by whole genome sequencing. The results finally confirmed A. dhakensis infection in the patient.

Table 1. Biochemical identification of A. dhakensis .

It is a subspecies of A. hydrophila , also known as Aquariumonas . It was originally isolated from children with diarrhea in Bangladesh during the period of 1993–1994 ( 18 ). In Beaz-Hidalgo et al. ( 19 ), ascertained that the Dakar subspecies of A. hydrophila and A. aquarium were the same species and that the Dakar subspecies were different from other subspecies of A. hydrophila . Therefore, the Dakar subspecies of A. hydrophila and A. aquarium were merged into a new species of A. dhakensis ( 19 ). Accumulating evidence shows that A. dhakensis is widely distributed in the environment, primarily in coastal areas, and can cause various human and animal infections, including gastroenteritis, wound infection, sepsis, respiratory tract infection, hepatobiliary disease, urinary tract infection, muscle necrosis, rhabdomyolysis, and necrotizing fasciitis ( 20 ). The reported mortality rate among patients with A. dhakensis extraintestinal infection varies from 25.5% to 37.5%, which is much higher than in those infected with other Aeromonas species (0%–14%) ( 20 , 21 ). Previous studies reported that A. dhakensis carries several virulence factors and exerts high toxicity on human blood cell lines ( 22 – 25 ) via exotoxins (act, aerA, hlyA, alt, ast, and other genes), type III secretion system (aexT, aopP, ascF-G, ascV, and other genes), extracellular enzymes (gcat, exu, ahyB, lip, ser, epr CAI, and other genes), adhesion factors associated with invasion (tapA gene), and flagella (laf and fla genes) ( 7 ). The high mortality rate and the abundance of virulence genes make it a crucial pathogenic species. However, the pathogenesis mechanism and regulation of toxicity remain unclear ( 26 ). The majority of Aeromonas bacteria carry at least one virulence gene. Act, hlyA, aerA, gcat, and lip genes related to cytolysis were detected in both enteric Aeromonas and exenteric Aeromonas to varying degrees, which cause hemolysis in the body.

Aeromonas dhakensis is susceptible to cefepime, aminoglycosides, fluoroquinolones, and tetracyclines, and hence, these drugs can be used for the treatment of the infection ( 22 , 27 ). Chao et al. ( 28 ) indicated that more than 80% of clinical strains are sensitive to third- or fourth-generation cephalosporins, aminoglycosides, fluoroquinolones, and imipenems. Therefore, the above drugs are still the first choice for treatment. However, A. dhakensis intrinsically harbors class B (metallo-β-lactamases, MBLs; CphA), C (AmpC cephalosporinase; AQU-1), and D β-lactamases (penicillinases). CphA has a specific substrate profile for hydrolyzing carbapenems; however, carbapenem therapy using CphA on Aeromonas infections remains controversial ( 29 , 30 ). It is notable that ertapenem is a breakthrough in the treatment of bacteremia caused by A. dhakensis ( 29 ). The best antibacterial options for treating A. dhakensis infection include fluoroquinolone or cefepime until susceptibility results are available ( 20 ). For severe pneumonia cases, we chose imipenem and linezolid for anti-infection treatment. Combined with blood culture and drug sensitivity test of the patient as shown in Table 2 , A. dhakensis was found to be susceptible to ceftazidime (MIC = 2 μg/ml), cefoperazone/sulbactam (MIC = 16 μg/ml), cefepime (MIC = 0.5 μg/ml), aztreonam (MIC ≤ 1 μg/ml), imipenem (MIC ≤ 0.25 μg/ml), meropenem (MIC ≤ 0.25 μg/ml), amikacin (MIC ≤ 2 μg/ml), ciprofloxacin (MIC ≤ 0.25 μg/ml), levofloxacin (MIC ≤ 0.12 μg/ml), tigecycline (MIC ≤ 0.5 μg/ml), and trimethoprim/sulfamethoxazole (MIC ≤ 20 μg/ml). A. dhakensis was found to be resistant to piperacillin/tazobactam (MIC ≥ 128 μg/ml). The drug resistance genes of the bacteria could not be ascribed to any carbapenemase genes (CphA, KPC, IMP, VIM, NDM, and OXA-48-like), extended-spectrum β-lactamase genes (CTX-M-1, CTX-M-9, CTX-M-15-like, TEM, and SHV), and Ampc enzyme genes (ACC and FOX). The pathogenic bacterial infection was susceptible to imipenem cilastatin sodium. Unfortunately, the patient died due to rapid disease progression.

Table 2. Drug sensitivity test of the patient.

Based on the diagnosis and treatment process of this patient, we realized that Aeromonas is not a common bacterium in doctors’ empirical diagnoses of community-acquired pneumonia patients. First, the pathogenic microorganisms responsible for hemoptysis in community-acquired pneumonia are Staphylococcus aureus , Mycobacterium tuberculosis , Streptococcus pneumoniae , Klebsiella pneumoniae , Aspergillus , and Mucor . Aeromonas , and infection with community-acquired pneumonia as the initial symptom and hemolysis lead to pulmonary hemorrhage, multiple organ dysfunction, and hemorrhagic shock, is rare. Second, the patient was admitted to the hospital with respiratory symptoms rather than the common symptom of diarrhea caused by Aeromonas infection, which is a rare manifestation of Aeromonas infection, and the occurrence of hemolytic uremic syndrome is again a rare clinical symptom. Third, based on the literature review, Aeromonas infection occurs in individuals with low immunity to the disease ( 31 ); however, this patient was young with no history of basic diseases or low immunity situation. In the present case, Aeromonas caused rapid progression, indicating that it could also infect the normal immune population and can also appear in severe manifestations. Fourth, although the patient had a clear manifestation of hemolytic uremic syndrome caused by Aeromonas infection, Escherichia coli is the most common pathogen causing the syndrome, followed by Shigella dysentery, Salmonella , Campylobacter , Yersinia , and enterovirus ( 32 , 33 ). Only two cases of Aeromonas causing hemolytic uremic syndrome have been reported to date ( 33 – 35 ), and hence, the clinical presentation of this patient is rare. Fifth, if the patient was admitted to the hospital when respiratory symptoms occurred, cephalosporins or quinolones were administered according to the experience of doctors in the treatment of community-acquired pneumonia in order to make a life-saving treatment attempt.

Data availability statement

The original contributions presented in this study are included in the article, further inquiries can be directed to the corresponding author.

Ethics statement

The studies involving humans were approved by the First Affiliated Clinical Research Ethics Review Committee of Chongqing Medical University. The studies were conducted in accordance with the local legislation and institutional requirements. The participants provided their written informed consent to participate in this study. Written informed consent was obtained from the relation for the publication of any potentially identifiable images or data included in this article.

Author contributions

DL: Writing – original draft, Writing – review & editing. LD: Writing – original draft, Writing – review & editing.

The author(s) declare that no financial support was received for the research, authorship, and/or publication of this article.

Conflict of interest

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Keywords : community-acquired pneumonia, hemoptysis, Aeromonas , hemolytic uremic syndrome, multiple organ dysfunction

Citation: Luo D and Dai L (2024) A 26-year-old man with multiple organ failure caused by Aeromonas dhakensis infection: a case report and literature review. Front. Med. 11:1289338. doi: 10.3389/fmed.2024.1289338

Received: 05 September 2023; Accepted: 29 February 2024; Published: 17 April 2024.

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*Correspondence: Liwan Dai, [email protected]