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Grey Literature: What is Grey Literature?

Finding and using grey literature as a research resource

What is Grey Literature?

The term grey literature is used to describe a wide range of different information that is produced outside of traditional publishing and distribution channels, and which is often not well represented in indexing databases.

A widely accepted definition in the scholarly community for grey literature  is ...

"information produced on all levels of government, academia, business and industry in electronic and print formats not controlled by commercial publishing" ie. 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: pros and cons

Uniqueness and currency v quality and longevity

Grey Literature can be a very important research resource.

  • It can record findings in niche or emerging research areas that are not addressed by the commercial publishers - who may have a more mainstream, profit based publishing strategy.
  • It can also be more current than formally published research literature which can take time to pass through a sometimes lengthy peer review and editorial publishing process

You should be aware of the need to assess and capture potentially useful resources

  • Grey Literature sources can vary hugely in terms of quality.
  • Scholarly publications such as books and journals pass through a formal publishing process and are subject to in depth editing review. In many cases there is a peer review process where draft versions are subject to a scrutiny process by a panel of experts.  Papers may be modified and improved in light of the expert feedback before reaching final published status. 
  • Not all grey literature material is subject to a similarly rigorous pre publication review process, so you should exercise caution and make your own assessment for quality, reliability and potential bias.  See the Evaluating Sources tutorial for more guidance on this.
  • Grey literature is often not formally published. For example, a report may be posted to a government department website or a poster presentation may be given at a conference. In theses cases 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 discovery later down the line.

Introductory video from the University of Guelph

If you prefer an audiovisual introduction, take a look at this short information video.

Some examples of Grey Literature

A wide, and growing, range of material can be considered as grey literature.


Not all these examples will be relevant to all researchers.  For example, clinical trial information is primarily of interest to health and medical research.  You should consider which types of information you are interested in before you begin searching as this will help you target and frame your online searching.


  • Blogs
  • Clinical trials
  • Conference papers/proceedings
  • Discussion Forums
  • Dissertations and theses
  • Email discussion lists
  • Government documents and reports
  • Interviews
  • Market reports
  • Newsletters
  • Pamphlets
  • Patents
  • Policy statements
  • Pre print articles
  • Research reports
  • Statistical Reports
  • Survey results
  • Tweets
  • Wikis
  • Working papers


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