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Literature Reviews

How to understand and write a literature review for an academic paper or research article.

Types of Publication

When deciding what to include in your review, it may help to understand what your options are and how to think about the different types of material means in terms of credibility as well as availability.



Primary research?

Peer-reviewed or edited by professional editors?

Published journal article/article of record Yes Yes
Pre/postprint Yes No
Conference paper Yes Yes
Book chapter Yes Yes
Monograph Yes Yes
Thesis/dissertation Yes No
Blog/website post Can be updates of research but not usually full results No
Newspaper article Secondary research - discusses primary research Yes
Grey literature Can be Yes
Dataset Yes No


Gray Literature: What It Is & Where to Find It

"Gray" literature is defined as information sources published outside of the traditional journal process and thus, while the text has generally been edited in some way, it does not go through the peer review process. 

Types of grey literature include:
  • Hard to find studies, reports, or dissertations
  • Governmental or private sector research
  • Clinical trials - ongoing or unpublished

(Taken from “Literature Search: Databases and Gray Literature,” NIH Library, 2019)


In the publication process, preprints are the draft text written by the original author(s) as it is submitted to the journal but prior to peer review. 

Some fields have long incorporated preprints into the dissemination of research, such as physics and computer science, while others, including the biomedical fields, have only recently begun to do so. When deciding whether to use a preprint in your literature review, be sure to identify it as such in your text and verify if there has been a publisher version of record, as that might be the document better cited.