Grey Literature

The databases below are designed specifically to search for hard-to-find grey literature. Note that many of these databases have unsophisticated search systems, so it can be difficult to build a focused search strategy for them. For assistance using these databases, reach out to your liaison librarian.

• OpenGrey

  OpenGrey, is a European database containing technical or research reports, doctoral dissertations, some conference papers, some official publications, and other types of grey literature.

• CADTH Grey Matters

  CADTH's Grey Matters resource is a free online tool for finding health-related grey literature that are not published commercially and which may be inaccessible via bibliographic databases.

One of the best ways to find relevant grey literature is to go straight to the websites of organizations that do research and work in your area of interest, as these organizations often produce reports, white papers, and other forms grey literature. In addition to using your own professional knowledge, you can use the sources below to identify relevant organizations in your research area.

• Harvard Catalyst Policy Atlas

  The Harvard Catalyst Policy Atlas is a comprehensive database of policy and public health data. Searching or browsing by topic is a good way to find organizations doing research in a particular area.

• MedlinePlus List of Organizations

  MedlinePlus's list of organizations is a comprehensive listing of organizations and agencies that are trusted enough to be cited on MedlinePlus, the leading consumer health information website.

• Think Tank Search This link opens in a new window

  A customized Google search created by Harvard Kennedy School Library & Info Services to search over 650 think tank and research center sites for policy and reports

• NGO Custom Search

  This custom search looks for documents produced by US-based non-governmental organizations.

• IGO Custom Search

  This custom google search looks for resources produced by intergovernmental organizations such as WHO, NATO, and the UN.

While most academic databases do not include grey literature, some of our databases include selected grey literature, particularly conference proceedings and dissertations. The list below introduced some databases that include grey literature and the types of content they include. Developing a comprehensive search with lots of keywords in the following databases will help you include grey literature without having to search many additional sources.

Government agencies produce a wealth of information via reports, white papers, policy papers, and more. The library's A-Z database list contains a wide variety of recommended government websites to find high-quality information. See below for a list of some key government resources to consider for your search.

• Agency for Healthcare Research and Quality (AHRQ) This link opens in a new window

  Govt reports commissioned to assist public- and private-sector organizations in their efforts to improve the quality of health care in the United States; comprehensive, science-based information on common, costly medical conditions and new health care technologies and strategies, reviews of relevant scientific literature on a wide spectrum of clinical and health services topics, technical reports on methodological topics, and other types of evidence synthesis-related reports.

• NARIC Knowledgebase This link opens in a new window

  The NARIC Knowledgebase contains more than 3,000 resources ranging from organizations and agencies to periodicals and Web resources. Each listing includes contact information, an abstract, and highlights of the products and services offered.

• National Center for Complementary and Integrative Health This link opens in a new window

  NIH research to help answer important scientific and public health questions about complementary and integrative health approaches; works to determine what is promising, what helps and why, what doesn’t work, and what is safe, and provides a database of research, recommendations, and patient information.

• NIOSHTIC-2 This link opens in a new window

  Searchable bibliographic database of occupational safety and health publications, documents, grant reports, and other communication products supported in whole or in part by NIOSH, the US National Institute for Occupational Safety & Health

• REHABDATA This link opens in a new window

  Abstracts for over 200,000 documents covering physical, mental, and psychiatric disabilities, independent living, vocational rehabilitation, special education, assistive technology, law, employment, and other issues as they relate to people with disabilities; spanning 1956 to the present; includes some full-text. Now includes the CIRRIE Database of International Rehabilitation Research.

Trials registers

The two key registers you should start with are ClinicalTrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP).

The ICTRP enables searching across multiple national registers. ClinicalTrials.gov is an increasingly important international register for systematic reviews. It can be searched through the ICTRP, but its more advanced search features make an additional, direct search of this register worthwhile to find the largest possible number of relevant studies.

Not only do trials registers provide access to ongoing, unpublished studies, but they also provides access to a growing repository of information on completed studies, many of which have results posted on the site (irrespective of the publication status of the study). 

• ClinicalTrials.gov 

• International Clinical Trials Registry Platform (ICTRP)

Preprints are versions of research articles that are posted in a public repository BEFORE being accepted to a journal or undergoing peer review. They can be a great way to follow current research on a topic without waiting the long publishing process. Because preprints have not been peer reviewed, it is important to critically appraise them yourself. 

Important preprint servers in the health sciences are listed below. 

• Directory of Preprint Server Policies and Practices

• arXiv.org

• medRxiv

• bioRxiv

• ChemRxiv

• PsyRxiv

• MindRxiv

• SportRxiv

• F1000 Research

• EdArxiv

• SSRN

• Research Square

• OSF Preprints

Dissertations and theses are normally not indexed in general bibliographic databases such as MEDLINE or Embase, but there are exceptions, such as CINAHL, where nursing, physiotherapy, and occupational health dissertations are indexed, and PsycINFO, where dissertations in psychiatry and psychology are indexed. To identify relevant studies published in dissertations or theses, it is advisable to search specific dissertation sources. 

• Centre for Reviews and Dissemination
• LILACS
• OATD.org