Grey literature is defined as "Information produced by all levels of government, academia, business and industry in electronic and print formats that is not controlled by commercial publishing" (4th International Conference on Grey Literature, Washington 1999).
It includes reports (including technical and statistical reports), dissertations, theses, conference papers, technical & other trade papers, bibliographies and documents in repositories. (New York Academy of Medicine - Grey Literature Report).
You can find examples of specific resources by subject or discipline area by looking at the applicable Library Resource Guide.
"Grey literature plays an important role in the rapid and timely distribution of in-depth, recent, scientific and technical information. Grey literature provides access to a broad range of information and often contains new ideas." (Simkhada, 2004).
Searching the grey literature also offers the potential to balance any tendencies for publication bias (i.e., an increased likelihood of reporting positive or significant results), in the published literature. Research that is not published in journals but available in other formats (such as reports, theses or conference proceedings) is often much more detailed, is more recent and can be more rapidly disseminated. Due to the competitive and time consuming nature of publishing in peer-reviewed academic journals, some research may never make it into journals and would therefore be inaccessible to interested parties without the availability of grey literature." (Primary Health Care Research and Information Service (Flinders University))
Use grey literature for:
Key questions to ask include:
As with all information, it is important to identify whether the information contained in grey literature is credible.
Be aware of private research organisations, drug companies, 'think tanks' etc as they have their own commercial, political or social interests and biases.
The AACODS Checklist, (Authority, Accuracy, Coverage, Objectivity, Date, Significance) by Jess Tyndal at Flinders University, is a good resource on evaluating grey literature.
Also check out our guidelines for evaluating information you find online.
Google and Google Scholar can be good sources for finding grey literature. To avoid unwanted results, use operators to limit your search.
Google Operators To search Google by domain or site, use
Google Advanced (google "Google Advanced Search" to find search interface) Provides rudimentary search fields as well as limiters including region, site/domain, file type or where the search terms appear on the page. Google Scholar uses similar search strategies but with results limited to academic resource