What is grey literature?
Grey literature is defined as "multiple document types produced on all levels of government, academics, business, and organization in electronic and print formats not controlled by commercial publishers i.e. where publishing is not the primary activity of the producing body." GreyNet.
In effect this means that most grey literature will not be searchable or accessible via conventional databases.
Why include grey literature in your review?
Grey literature includes:
Searching for grey literature
There are numerous sources of grey literature including universities, libraries, governments, organisations and websites. See the adjacent box 'Sources of Grey Literature' for websites / databases designed to mine grey literature in specific fields. Also search large library catalogues e.g. WorldCat or the the National Library of Australia's Trove.
Web Search Tips
"in recent years it has become clear that the likelihood of finding a critical unpublished study or study data that changes key summary outcomes may be greater than we had once thought. For this reason, we are recommending searching these other sources for studies that might otherwise not be identified... we temper our recommendation for searching other sources with a recommendation to be selective and to choose the sources to be searched where it makes most sense." (Balshem, H. et al. 2013. Reference below)
Evaluating grey literature
As with all evidence, it is important to appraise grey literature and ascertain its quality / relevance. A critical appraisal checklist for grey literature was developed by Jess Tyndall, Flinders University in 2010:
AACODS
Authority - is the author credible / reputable?
Accuracy - is there a clearly stated aim & methodology which has been met? Supported by authoritative references / sources? Is it representative of other work in the field / provides a valid counterbalance?
Coverage - are any limits clearly stated?
Objectivity - any obvious bias?
Date - does the date relate to the content? Can't find the date? Be very wary.
Significance - is it relevant? Does it enrich / impact on your research?
Search tools for finding international grey literature
Search tools for finding Australian grey literature
Dissertations / theses
Government sources
How to find conference proceedings / papers / posters
The collection of papers / posters presented at a conference are know as conference proceedings. These may be published in book format, as special issues of a journal, or as a serial.
Conference proceedings are often difficult to find. You may be able to find them by searching a relevant library catalogue using the complete conference title or the location and year. If not successful try searching WorldCat.
Google - many societies and organisations publish their proceedings on their website. You can also try searching for the title as a "phrase" (using quotation marks).
The following databases may also have conference papers on your topic:
Embase
MEDLINE
Trial Registries