Grey (gray) literature can be defined as:
"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."
(ICGL Luxembourg definition, 1997 - Expanded in New York, 2004).
Grey literature can include:
- Technical or research reports from government agencies
- Reports from scientific research groups
- Working papers from research groups or committees
- Conference and meeting proceedings/abstracts
- Dissertations and theses
- Archival materials
- Unpublished or ongoing studies
- Clinical practice guidelines not published in journals
- Informal communications with experts ... and so much more ...
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For Systematic Reviews
Systematic frameworks for searching the grey literature
The Grey Matters online checklist tool produced by The Canadian Agency for Drugs and Technologies in Health (CADTH) is excellent when searching for drug evidence.
Health Technology Assessment on the Net: 2015, produced by the Institute of Health Economics (Canada), complements the CADTH checklist.
Another master list of grey sources is Databases for Research in Health, produced by Jess Tyndall at Torrens University. This version dates from 2016. The list, originally created to support primary health care and public health postgraduates, has been expanded to include clinical and biomedical resources. Websites are not included unless they have a strong searchable component, and the content is organised in such a way that it can be usefully interrogated by researchers.
Jess Tyndall is also the author of the AACODS checklist for evaluating the quality of grey literature.