What is grey literature?
Grey literature is information which has been published informally or non-commercially, or remains unpublished. It can appear in many forms, including conference papers, government reports, statistics, patents, patient information sheets or posters.
Grey literature is not usually peer-reviewed, but may still be good, reliable information. Appraisal of grey literature should be conducted with the same rigour as with peer review.
See the PHCRIS Introduction to Accessing the Grey Literature and the HLWiki page on grey literature for a more detailed overview. They are aimed at medical researchers but are relevant to anyone searching for grey literature.
The University of South Australia has a comprehensive Grey Literature guide.
Why is grey literature important?
"Published trials tend to be larger and show an overall greater treatment effect than grey trials. This has important implications for reviewers who need to ensure they identify grey trials, in order to minimise the risk of introducing bias into their review"
Hopewell et al. Grey literature in meta-analyses of randomized trials of health care interventions. Cochrane Database Sys. Rev. 2007.
"failure to identify trials reported in conference proceedings and other grey literature might affect the results of a systematic review"
188.8.131.52 Grey literature databases. Cochrane Handbook for Systematic Reviews of Interventions.
Grey literature can be found through a number of methods, including:
This guide lists some resources to help you get started, but is not comprehensive - you'll need to look elsewhere as well.
Grey literature is hard to find - be systematic!
Before you start searching, ask yourself:
This will influence how and where you search.
Tips for using search engines:
Evaluating grey literature
You should evaluate every source you use, but it's particularly important to do so when using grey literature.
The quality of grey literature can vary greatly as it comes from a wide range of sources and doesn't go through the traditional editorial process.
The AACODS checklist is designed to enable evaluation and critical appraisal of grey literature.
The checklist includes the following areas:
Tyndall, J. AACODS Checklist. Flinders University, 2010. Available from http://dspace.flinders.edu.au/dspace/
Selected databases, repositories and website gateways:
Library databases that include some grey literature:
Many other databases include conference proceedings, check their descriptions on the databases library guide.
See the library's government publications guide for more detailed advice on locating documents from Australia and other countries.
Selected Australian government sites:
Search tools, directories and newsletters: