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EES2200 Advanced Seminar in Environmental Science (PhD)

This guide will help PhD Environmental Sciences students at UTSC access key resources for research, learn about publishing and scholarly communication, and more.

What is a Literature Review

A literature review is a survey of everything that has been written about a particular topic, theory, or research question. It may provide the background for larger work, or it may stand on its own. Much more than a simple list of sources, an effective literature review analyzes and synthesizes information about key themes or issues.

Why write a literature review?

  • To discover what has been written about a topic already.
  • To determine what each source contributes to the topic.
  • To understand the relationship between the various contributions, identify and (if possible) resolve contradictions, and determine gaps or unanswered questions.

What's Involved?

Research to discover what has been written about the topic.

Critical Appraisal to evaluate the literature, determine the relationship between the sources and ascertain what has been done already and what still needs to be done.

Writing to explain what you have found.

Focus on Writing


The introduction should identify your topic, some discussion of the significance of that topic and a thesis statement that outlines what conclusion you will draw from your analysis and synthesis of the literature. If your literature review is part of a larger work, explain the importance of the review to your research question.


In the body, discuss and assess the research according to specific organizational principles (see examples below), rather than addressing each source separately. Most, if not all, paragraphs should discuss more than one source. Avoid addressing your sources alphabetically as this does not assist in developing the themes or key issues central to your review.


The conclusion should provide a summary of YOUR findings from the literature review. Explain what your analysis of the material leads you to conclude about the overall state of the literature, what it provides and where it is lacking. You can also provide suggestions for future research or explain how your future research will fill the gaps in the existing body of work on that topic.

© Allyson Skene. The Writing Centre, University of Toronto at Scarborough. See terms and conditions for use at

Research & Evaluate

Gather sources

  • Focus your topic: A literature review aims to cover all of the research on a given topic. If the topic is too large, there will be too much material.

  • Read with a purpose: Although you will need to briefly summarize sources, a good literature review requires that you isolate key themes or issues related to your own research interests.

Evaluate sources

For each source, consider: 

  • Credentials: Is the author an expert? 
  • Argument/Evidence: Does the evidence support the conclusion? Is the argument or evidence complete?

When comparing sources, consider: 

  • Conclusions: Does all research arrive at the same conclusion or are there differing opinions? What evidence or reasoning are the differences based on? 
  • Gaps or omissions: What questions are raised by the literature?

Ways to Organize your Literature Review

Organize by Theme

Use it when explaining key themes or issues relevant to the topic. This is the most common way to organize literature reviews.

A literature review of 31 relevant articles published between January 1999 and March 2004 identified 12 categories of neighborhood characteristics relevant to maternal and child health: income/wealth, employment, family structure, population composition, housing, mobility, education, occupation, social resources, violence and crime, deviant behavior and physical conditions.

[Example adapted from Rajaratnama, J.K., Burke, J.G. & O’Campo, P. (2006). Maternal and child health and neighborhood context: The selection and construction of area-level variables. Health and Place, 12, 547-556.]

Organize by Methodology (also called a methodology review)

When discussing interdisciplinary approaches to a topic or when discussing a number of studies with a different approach.

In dentistry, fluorescent imaging been used for many applications revealing a variety of information about bonded restorations. This review evaluates the different methods used in this area with the intent of determining if standardized methodologies exist.

[Example adapted from D’ Alpino, P .H.P. et al (2006).Use of fluorescent compounds in assessing bonded resin-based restorations: A literature review Journal of Dentistry34 623-634.]

Organize by Chronology

When historical changes are central to explaining the topic.

A literature review is presented on the evolution of water pollution management and its impact on land pollution from 1900 to 2000 within a hypothesis of whether we could have done more, sooner. Stream pollution science in the context of the fundamental sanitary engineering concepts of reasonable use and assimilative capacity is examined in light of evolving regulatory frameworks from the early 1900s, when regulation and standards were mostly lacking, to the zero discharge goals and comprehensive federal command/control regulations of the late 20th century.

[Example adapted from Shrifin, N.S. (2005). Pollution Management in the Twentieth Century. Journal of Environmental Engineering, 131, 676-691.]