Grey literature refers to both published and unpublished research, produced by government, academia, business and industry, that is not controlled by commercial publishers.
Some examples of grey literature include:
The Internet is now a major source for dissemination and retrieval of grey literature and often is a good starting point to a topic area. Search or browse the websites of key organisations in your research area. These may include: government agencies, academic or research institutes, professional associations, and advocacy groups. Depending on the focus of your topic, the following sources may be useful:
As well as journal articles, many library databases also index other types of literature including conference papers, reports, theses and government documents.
|Most library databases provide the facility to limit by publication or document type, which will allow you to narrow your search to grey literature sources.|
More grey literature databases are available through the Cochrane Handbook (4.S1 Technical Supplement, 1.1.6)
Search engines such as Google are also useful when searching for grey literature. Note that:
When you perform a Google search you can also limit to particular domains or by file type. Most of the grey literature available on the Web is in the form of PDF documents. Also consider restricting your search to the .org and/or .gov domains.
e.g. vaccination rural Australia filetype:pdf or vaccination rural Australia site:org
Grey literature is usually not subject to the same peer-review process or quality checks as books, journals and other commercially published literature. It is important to critically evaluate grey literature to ensure it is of a suitable quality to include in your systematic review.
The AACODS checklist is a useful tool for evaluating grey literature:
Have a look at this PowerPoint presentation for a comprehensive overview of grey literature in the Heath Sciences (click on the image to view):