Grey literature can be a rich resource when researching for a literature review or dissertation topic. It can help you find current and emerging research, viewpoints of individuals such as patients and consumers, and more in depth or practical coverage of topics.
It can also help you to mitigate against 'publication bias’, where studies showing positive research results are much more likely to be published in journals. A search for grey literature will help to ensure that all relevant results, even if negative, are located.
'Grey literature' refers to a wide range of information which is not formally or commercially published, and which is often not well represented in library research databases. Here we’ll give several top tips for finding and using grey literature.
What is grey literature
While there are a number of definitions for grey literature, in the academic community a widely accepted definition is:
“information produced on all levels of government, academia, business and industry in electronic and print formats not controlled by commercial publishing i.e. where publishing is not the primary activity of the producing body.”
From: Third International Conference on Grey Literature in 1997 (ICGL Luxembourg definition, 1997 - Expanded in New York, 2004).
Grey literature can include blogs, clinical trial registers, theses, government documents, NGO reports, policy statements, and more. The primary grey literature in the sciences may differ from grey literature in the arts and humanities.
Where to find grey literature
Because of the varied nature of grey literature, you may need to search in several places to find different types of publications.
The Library subscribes to several useful online resources you can use to find grey literature. A few key ones are listed here, and you can find even more on the Grey Literature subject guide.
- Policy documents: check out Overton and Policy Commons. And for an introduction to using Policy Commons, join us for the Dissertation & Thesis Festival session on Policy Commons: bringing real-world knowledge into research on 26th Feb 2026.
- Dissertations and theses: There are databases and online resources that allow you to search for theses and dissertations both at the University of Edinburgh and elsewhere.
- Clinical trials: There are databases and online resources, such as clinical trial registries, that can help you find published, unpublished, and ongoing clinical trials.
Things to watch out for
Some types of grey literature is often not formally published so you need to consider the longevity of the resource. Something may be available on the web, or a blog for a short period only and may not be formally archived. Make sure you keep a record of material you wish to use/reference - as it may not be there for discovering later down the line!
Grey literature sources can vary hugely in terms of quality, and can be regarded as less prestigious and less organised than published literature as it's not always peer reviewed or fully edited. To critically evaluate grey literature, you might want to use a checklist to guide you in gauging the quality of the research, such as the Authority, Accuracy, Coverage, Objectivity, Date, Significance (AACODS) checklist by Tyndall (2010).
Further help
Bookmark the Grey literature subject guide for resources and advice about finding and using grey literature in your research and studies.
For a case study about incorporating grey literature into a review along with loads of helpful advice, read Lolita Alfred’s 2020 article The challenges and opportunities for incorporating gray literature in an integrative literature review in Sage Research Methods.
Look out for the next Library Bitesize session on grey literature for evidence synthesis, or watch a recording of a previous session on Media Hopper.
References
You can also use these as sources of even more guidance.
Tyndall J. Authority, Accuracy, Coverage, Objectivity, Date, Significance
(AACODS) Checklist. 2010. https://fac.flinders.edu.au/dspace/api/core/bitstreams/e94a96eb-0334-4300-8880-c836d4d9a676/content
Alfred, L., (2020). The challenges and opportunities for incorporating gray literature in an integrative literature review. In Sage Research Methods Cases: Medicine and Health. SAGE Publications, Ltd., https://doi.org/10.4135/9781529740844
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