The Fourth International Conference on Grey Literature in 1999 arrived at the following definition:
"That which is produced on all levels of government, academics, business,
and industry in print and electronic formats, but which is not controlled by
commercial publishers". Examples of grey literature include conference abstracts,
presentations, proceedings; regulatory data; unpublished trial data; government publications; reports
(such as white papers, working papers, internal documentation); dissertations/theses; patents; and policies & procedures.
Inclusion of grey literature into a systematic review is recommended in order to help minimize publication bias. The inclusion of grey literature in systematic reviews is widely recognized as important and international organizations have incorporated this information in their guidelines and manuals for working on reviews and meta-analyses.
Searching the grey literature can be a daunting task. You should search those resources that make the most sense for your research question. At a minimum, consider searching Abstracts and Conferences. If your question involves drugs and interventions, check trial registries and pharma data. Also, check out the papers and reports of relevant stakeholder organizations.
The links below may shed some additional light on the process.
Use the same criteria to evaluate the literature as those used to evaluate any kind of information.
|Source of the report||Locate the source of the report. Check if this is a reliable author, organization or source.|
|Transparency of methods||It should be clear where data and other types of information came from, how it is analyzed and how the final report was compiled.|
|Currentness:||Find the data a report was issued. If the report (or other material) is older, try to find a more recent version or an update|
Tip: The AACODS Checklist (pdf), designed for evaluation and critical appraisal of Grey Literature.
Most Grey Literature is found using hand-searching or in databases that do not offer systematic search. However, for systematic reviews, reproducibility of the search is key. Make sure you document your searches well.
Networked Digital Library of Theses and Dissertations
ProQuest Dissertations & Theses
Official Information Sources of the Prime Minister of the Republic of Kazakhstan (in Russian and Kazakh)
Open Government of the Republic of Kazakhstan (in Russian and Kazakh)
Repositories are collections of research produced by an institution's researchers. Institutions can be governmental, organizational, and academic, such as Universities. Often contain electronic theses.
Nazarbayev University Repository is an institutional electronic archive for long term storage, accumulation and provision of long-term and reliable open access to scientific research results and intellectual products of the academic community of Nazarbayev University associated with them.