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Dissertations: Literature review

What is a literature review?

What is a literature review?

The term “literature” in “literature review” comprises scholarly articles, books, and other sources (e.g. reports) relevant to a particular issue, area of research or theory. In a dissertation, the literature review illustrates what the literature already says on your research subject, providing summary, synthesis and critical analysis of such literature. It is generally structured by topic, starting from general background and concepts, and then addressing what can be found - and cannot be found - on the specific focus of your dissertation. Indeed, the literature review should identify gaps in the literature, that your research aims to fill. 

What is the purpose of a literature review in a dissertation?

  • To some extent, it provides background information, concepts, theories and analytical models that will be used in the discussion/analysis chapter(s) of the dissertation.
  • To some extent, it shows the limitations and gaps in the existing literature. This justifies your research and shows why the literature doesn’t fully answer your research question (or hypothesis).


Find in this page guidance on how to write a literature review, step by step.

  1. Framing the research question/hypothesis
  2. Identifying relevant work
  3. Assessing the quality of studies
  4. Structuring your work
  5. Synthesising information
  6. Expressing critical analysis 

1) Framing the research question/hypothesis

In order to know what literature you need to research, you need to know what question you need to answer! The literature review is the first attempt to answer the research question. It provides background on what is known about the subject, but also exhibits a gap, which your research should fill. To learn more about research questions and hypotheses see First Steps.  

2) Identifying Relevant Work

What an exciting part of your research! Here is where you investigate and learn more about your research topic. You can follow these steps: 

  • Broaden your search, getting an overview of all the issues involved in your topic. 
  • Draw an outline of your literature review, identifying the topics that are most relevant, and deciding in what order you'd like to address them. 
  • Identify more literature that addresses the specific issues you want to present in your review.

Broaden your search

Initially, broaden your search not to overlook relevant results.

Mind mapping for generating ideas and creative thinking

Place a blank sheet in landscape position and write the essay question in the middle. Draw branches from the question, which are possible ideas and topics to include in the essay. Add sub-topics (“leaves”) and connect ideas and evidence from your reading. You can use colours and images to stimulate your thinking. Some leaves can be used as key words for your search.

Play with your key words

Look for synonyms and related terms:


Topic: “The impact of Covid-19 on the British environment”

What to search?

Covid-19 British Environment

Synonyms and related words:

Coronavirus; SARS-CoV-2

Pollution; air quality; waste

Britain; United Kingdom, UK, England, Scotland, Wales, British Isles, Ireland.

Be selective: get relevant sources

Keep an open mind but only look for and use sources which are relevant for your dissertation (unless of course you are reading for interest!). After an initial phase of broadening your research, you should narrow it down and focus on the issues you want to deal with in your literature review.

How to find sources

Try different search tools:

Internet (for example, Google): will give you the largest number of results, but most of the results will not be peer-reviewed and may not be reliable. You can use it to have a general overview of your research topic.

Library search: this will give you only academic, peer-reviewed sources. All these resources are accessible to you online and/or in the library. See the guide on Library Search.

Library subject guides: these provide subject-specific research support, including access to subject-specific books, journals, databases, legal materials, archives etc. They also provide guidance on citing and referencing. Check your Library subject guides.

Contact your Academic Liaison Librarian: the Academic Liaison Librarian will be able to suggest resources, search tools and research techniques that can help you get a head start on your research. You can find the details of your Librarian here.

Google Scholar: this provides scholarly results as well as technical reports from governments and other organisations, and other academically valuable sources like patents, theses etc. Google Scholar allows the useful feat of forward citation tracking (finding newest sources that cite a given source) that can help you find what other literature comments on a certain source. It has to be noted, however, that not all resources on Google Scholar are peer-reviewed and reliable. See the library guide on using Google Scholar.

3) Assessing the Quality of the Sources

CRAAP test

Think of how CRAAP the text you are reading is!


CRAAP = Currency, Relevance, Authority, Accuracy, Purpose


How recent/old is your source? In certain fields it is very important that the sources are as recent as possible. In others, like history, a source or document from the past may be more valuable. 


Is the text relevant to your dissertation? Does it help fill some section and answer your research question?


Who is the source of the information? Where was it published? Was it peer-reviewed?


What evidence is the source relying on? Is the evidence up to date? Is the evidence correctly interpreted? Is the argument made in the source logical? Is the methodology sound?  


What's the purpose of the source? Is there an agenda? If it's a company report, it may try to portray the company in a positive light. If it's a government report, it may try to defend government policies. 

Triple perspective

In order to better evaluate a piece of work, you need to compare it with other sources dealing with the same topic(s). This is a main function of the literature review. Try to adopt a triple perspective: 


4) Structuring the Literature Review

Uncertain about how to structure your literature review? Have a look at this revelatory video by Dr Jodie Salter and the University of Guelph. 

The literature review should have an introduction, a body and a conclusion.

As shown in the video, above, the body shall NOT be organised author by author. It should be organised by topic (normally, from general background to specific aspects of the subject your dissertation is dealing with). Some paragraphs can be organised chronologically (for example outlining the development of an idea throughout time), by method, by sector, or other criteria. 


This should be a paragraph that can include some of the following:

  • Outlining the scope of your literature review – sources, topics to be discussed / the aims of your review.
  • Where/how does your topic fit into the wider subject area.
  • Why the topic is important- is it an area of current interest/significance?
  • Highlight the relevant issues or debates that have characterised your field of research.
  • Has the topic been widely researched? Or not?
  • Signposting for the reader, explaining the organisation / sequence of topics covered in the review.


  • Provide strong sentences at beginnings of paragraphs: every paragraph shall deal with a topic or make a point. 
  • Signpost, showing the direction of your writing, and indicating your critical take on the sources you present. 
  • Use you own voice to comment on and evaluate the literature.
  • Identify gaps in the literature. 
  • Write "so what" summary sentences throughout the review to help the reader understand how the sections of your review are relevant to your research.
  • Use language to show confidence or caution, as appropriate: e.g. There is clearly a link... OR This suggests a possible link...
  • Avoid "he/she said...": always name the authors. Vary the reporting words. See the guide on Academic Voice and Language for more guidance on logic, signposting, reporting words etc. 


  • State how your literature review has met the review aim(s) outlined in the introduction.
  • Summarise and synthesise the main issues/themes that the literature review has presented in relation to your topic area and research questions.
  • Underline the gaps identified in the literature. This provides a rationale for your chosen dissertation topic.

5) Synthesis

How should you write, more specifically, the paragraphs within the body of your literature review? You will need to present a synthesis of the texts you read. Doug Specht, Senior Lecturer at the Westminster School of Media and Communication, explains synthesis for us in the following video. 

What is synthesis?

Synthesis is an important element of academic writing, demonstrating comprehension, analysis, evaluation and original creation. 

  • With synthesis you extract content from different sources to create an original text. While paraphrase and summary maintain the structure of the given source(s), with synthesis you create a new structure. 
  • The sources will provide different perspectives and evidence on a topic. They will be put together when agreeing, contrasted when disagreeing. The sources must be referenced. 
  • Perfect your synthesis by showing the flow of your reasoning, expressing critical evaluation of the sources and drawing conclusions. 
  • When you synthesise think of "using strategic thinking to resolve a problem requiring the integration of diverse pieces of information around a structuring theme" (Mateos and Sole 2009, p448).
  • Synthesis is a complex activity, which requires an high degree of comprehension and active engagement with the subject. As you progress in higher education, so increase the expectations on your abilities to synthesise.

How to synthesise in a literature review:

  1. Identify themes/issues you'd like to discuss in the literature review. Think of an outline. 
  2. Read the literature and identify these themes/issues. 
  3. Critically analyse the texts asking: how does the text I'm reading relate to the other texts I've read on the same topic? Is it in agreement? Does it differ in its perspective? Is it stronger or weaker? How does it differ (could be scope, methods, year of publication etc.). Draw your conclusions on the state of the literature on the topic. See next box for more tips on critical analysis.
  4. Start writing your literature review, structuring it according to the outline you planned. 
  5. Put together sources stating the same point; contrast sources presenting counter-arguments or different points. 
  6. Present your critical analysis. 
  7. Always provide the references.

The best synthesis requires a "recursive process" whereby you read the source texts, identify relevant parts, take notes, produce drafts, re-read the source texts, revise your text, re-write... (Mateos and Sole, 2009)

What is good synthesis? 

The quality of your synthesis can be assessed considering the following (Mateos and Sole, 2009, p439): 

  • Integration and connection of the information from the source texts around a structuring theme.
  • Selection of ideas necessary for producing the synthesis.
  • Appropriateness of the interpretation. 
  • Elaboration of the content. 


Original texts (fictitious):

Animal testing is necessary to save human lives. Incidents have happened where humans have died or have been seriously harmed for using drugs that had not been tested on animals (Smith 2008).  

Animals feel pain in a way that is physiologically and neuroanatomically similar to humans (Chowdhury 2012).  

Animal testing is not always used to assess the toxicology of a drug; sometimes painful experiments are undertaken to improve the effectiveness of cosmetics (Turner 2015)

Animals in distress can suffer psychologically, showing symptoms of depression and anxiety (Panatta and Hudson 2016).



Animal experimentation is a subject of heated debate. Some argue that painful experiments should be banned. Indeed it has been demonstrated that such experiments make animals suffer physically and psychologically (Chowdhury 2012; Panatta and Hudson 2016). On the other hand, it has been argued that animal experimentation can save human lives and reduce harm on humans (Smith 2008). This argument is only valid for toxicological testing, not for tests that, for example, merely improve the efficacy of a cosmetic (Turner 2015). It can be suggested that animal experimentation should be regulated to only allow toxicological risk assessment, and the suffering to the animals should be minimised.  

6) Criticality

The literature review of a dissertation should include critical analysis. You cannot simply juxtapose the literature you find: you have to evaluate and draw conclusions from it. You can use the CRAAP test (box above) and find guidance on critical reading here.

Paragraph level 

Try expressing your voice in each paragraph of your literature review. Write strong paragraphs. In strong paragraphs your voice can be heard in the topic sentence, development (where you analyse and compare/contrast the sources, sometimes as individual pieces, sometimes in a synthesis) and, even more easily, in the concluding sentence, where you present the "therefore" of the paragraph.

How to express criticality at the paragraph level: 

  • Identify the significance of the sources, and why the points they are making are relevant 
  • Make connections between the sources
  • Compare and contrast sources, literatures 
  • Accept/adopt points made by the sources, with reasons 
  • Reject the points made by the sources, with reasons (e.g., limitations in the methodology; out of date; limited scope; geographical delimitation)
  • Indicate the position you are taking in your own work on the theories and concepts presented by the sources
  • Show how limitations in the existing literature create a research gap for you
  • Organise the materials synthesising them in an original way, that sheds new light on the topic. 

Literature review level

Try to take ownership of the literature review. Remember the purposes of the review (providing background on the subject you are researching, and identifying a gap in the existing literature on this subject). Thus, throughout the review:  

  • Identify the key themes relevant to your subject matter 
  • Identify the most logical and effective order for your themes
  • Relate the sources back to the dissertation's research question
  • Shed new light on the topic
  • Draw conclusions on the existing literature 
  • Identify gaps in the literature 

Your literature review should present an argument (which you can recap in the concluding paragraph of the literature review) sounding like "the literature says/illustrates/reveals that... there are debates in the literature as of... it can be understood from the literature that... however, there are gaps in the literature... the literature does not specifically address (specific sector/location/population)... there is a lack of independent/recent studies on...  therefore in order to answer the research question(s) (you can repeat the question) this dissertation uses method xyz, as illustrated in the next section (if applicable)".


Ridley, D. (2008). The literature review: a step-by- step guide for students. London: Sage