What is grey literature?
Grey literature is defined as "that which is produced on all levels of government, academia, business and industry, in print and electronic formats, but which is not controlled by commercial publishers" Grey Literature Report
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:
More Information on Grey Literature:
Grey literature: Its emerging importance - Pappas C, WIlliams I. (2011) Journal of Hospital Librarianship (2011) p. 228-233.
State-of-the-evidence reviews: advantages and challenges of including grey literature - Benzies KM, Premji S, Hayden KA, Serrett K. State-of-the-evidence reviews: advantages and challenges of including grey literature. Worldviews Evid Based Nurs. 2006;3(2):55-61. PMID: 17040510
Searching for grey literature
There are numerous sources of grey literature including universities, libraries, governments, organizations 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 catalogs e.g. WorldCat
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"in recent years it has become clear that the likelihood of finding a critical unpublished study or study data that changes key summary outcomes may be greater than we had once thought.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:
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?
American Associations of Colleges of Nursing - The American Association of Colleges of Nursing is the national voice for baccalaureate and graduate nursing education.
CDC Stacks - CDC Stacks is a free, digital archive of scientific research and literature produced by the Centers for Disease Control and Prevention (CDC).
Clinical Trials.gov - ClinicalTrials.gov is a registry and results database of federally and privately supported clinical trials conducted in the United States and around the world.
Centre for Review and Dissemination - This databases provides easy access to quality assessed systematic reviews and economic evaluations and to health technology assessments conducted around the world.
Google Scholar -Google Scholar provides a simple way to broadly search for scholarly literature.
GreyNet International - GreyNet further seeks to identify and distribute information on and about grey literature in networked environments.
Health Research Projects in Progress (HSRProj) - Information about ongoing health services research and public health projects
Health Services Online - HSO provides free, online linkages to a comprehensive collection of top-quality courses and references in medicine, public health, pharmacy, dentistry, nursing, basic sciences, and other health sciences disciplines.
Kaiser Family Foundation -Kaiser serves as a non-partisan source of facts, information, and analysis for policymakers, the media, the health care community, and the public.
LILACS - LILACS, from the Latin American and Carribben Center on Health Information, is the most important and comprehensive index of scientific and technical literature of Latin America and the Caribbean.
Latin American Open Archives Portal(LAOAP) - The Latin American Open Archives Portal (LAOAP) is a project to build a scholars’ portal at the Latin American Network Information Center (LANIC) to improve access to social sciences grey literature produced in Latin America.
Mednar - Mednar is a free, publicly available deep web search engine that uses advanced federated search technology to return high quality results by submitting your search query - in real-time - to other well respected search engines. Mednar then collates, ranks and drops duplicates of the results.
New York Academy of Medicine Grey Literature - A bimonthly publication of The New York Academy of Medicine Library alerting readers to new grey literature publications in health services research and selected public health topics. In addition to this alert service, all resources are added and indexed in our Online Catalog.
National Information Center on Health Services Research and Health Care Technology (NICHSR) - HSR Information Central is not an index of all health services resources on the Web. Rather, it contains selective links representing a sample of available information. Items are selected for their quality, authority of authorship, uniqueness, and appropriateness.
National Library of Medicine Locator Plus - Generally doesn’t provide full text access to documents, but a good way to see what sort of government reports exists on a topic.
National Guidelines Clearinghouse ARHQ - This is a public resource for evidence-based clinical practice guidelines.
National Research Registry - Guide to research sponsored by, or of interest to Great Britain’s National Health Service.
NTIS - The National Technical Information Service serves as the largest central resource for government-funded scientific, technical, engineering, and business related information available today.
OpenDOAR - an authoritative directory of academic open access repositories.
OpenSIGLE (OpenGrey) - System for Information on Grey Literature in Europe.
Partners in Information Access for Public Health Workforce - Good collection of links to Grey Literature resources in Public Health including newspapers, reports and guidelines.
Robert Wood Johnson Foundation (publications & research) - The mission of the Robert Wood Johnson Foundation is to improve the health and health care of all Americans.
Virginia Henderson Global Nursing e-Respository - offer nurses, in all roles around the globe, online access to reliable nursing information that can be easily utilized and shared.
World Wide Science.org - is a global science gateway comprised of national and international scientific databases and portals.
World Health Organization Current Bibliography - Catalogs of publications by the World Health Organization and affiliated agencies including technical and policy documents.