The Twelfth International Conference on Grey Literature in Prague in 2010 arrived at the following definition:
"Grey literature stands for manifold document types produced on all levels of government, academics, business and industry in print and electronic formats that are protected by intellectual property rights, of sufficient quality to be collected and preserved by libraries and institutional repositories, but not controlled by commercial publishers; i.e. where publishing is not the primary activity of the producing body."
Examples of grey literature include: conference abstracts, presentations, proceedings; regulatory data; unpublished trial data; government publications; reports (such as white papers, working papers, internal documentation); dissertations/theses; patents; and policies &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.
Grey literature is not information that has been commercially published, therefore it includes studies that show positive results and failures. Failures are just as important as the positive results because evidence-based information includes both. Additionally, grey literature helps reduce publication bias and creates more balanced research and information within a systematic review.
Depending on what your topic is there are various options when trying to locate grey literature. Locating grey literature can feel daunting at times, so concentrate on abstracts or conference proceedings, unless you are researching a drug or intervention in pharmacology; then you would focus on clinical trials or pharma data.
Below are some links regarding the importance of grey literature:
Grey Matters! Find Grey literature
"Gray literature: An Important Resource in Systematic Reviews"
Grey Matters: A Practical Tool for Searching Health-Related Grey Literature
NY Academy of Medicine Grey Literature Report
This report is a bimonthly publication of The New York Academy of Medicine (NYAM) alerting readers to new grey literature publications in health services research and selected public health topics. The database platform is keyword searchable and serves as an archive for the cataloged reports.
OpenGrey: System for Information on Grey Literature in Europe
The System for Information on Grey Literature in Europe, is an open access database to 700.000 bibliographical references of grey literature produced in Europe and allows you to export records and locate the documents in many research disciplines.
The Grey Literature Network Service was founded in 1992. The goal of GreyNet is to facilitate dialog, research, and communication between persons and organizations in the field of grey literature. GreyNet further seeks to identify and distribute information on and about grey literature in networked environments
Theses & Dissertations--OhioLINK (2000 - present)
A catalog of dissertations, theses and published material based on theses and dissertations. This catalog is created by OCLC member libraries worldwide and includes dissertations, theses, etc. in all subject areas.
Dissertation & Theses-- Proquest (1861- present)
Contains more than 2 million entries for doctoral dissertations and master's theses. The database includes citations for materials ranging from the first U.S. dissertation, accepted in 1861, to those accepted as recently as last semester. Since 1997, new publications have been available electronically, and many publications can be ordered through the system for a fee. The database represents the work of authors from over 1,000 North American graduate schools and European universities.
This database offers access to health care books, nursing dissertations, selected conference proceedings, standards of practice, educational software, audiovisuals and book chapters, as well as Evidence-Based Care Sheet. Searchable cited references for many journals are also included. CINAHL Plus with Full Text provides full text 337 of journals, plus legal cases, clinical innovations, critical paths, drug records, research instruments and clinical trials. PDF backfiles to 1937 are also included.
Cochrane is for anyone interested in using high-quality information to make health decisions. Whether you are a doctor or nurse, patient or career, researcher or funder, Cochrane evidence provides a powerful tool to enhance your healthcare knowledge and decision making.
TRIP (Turning Research Into Practice) Database
Bristol-Myers Squibb Clinical Trial Registry
Eli Lilly Company Clinical Trial Registry
Pfizer Oncology Clinical Trials