Grey Literature

Grey Literature

Grey Literature refers to either published or unpublished research, that is not controlled by commercial publishers. It can be derived from a variety of sources such as central and local government, academia, business and industry, as well as charities and not-for-profit organisations. It can be both national and international. 

Examples include:

  • Government reports/White papers                              

  • Statistical publications

  • Clinical Trials

  • Clinical Guidelines/General Guidelines

  • Policy statements

  • Research reports

  • Fact sheets

  • Conference proceedings/papers/posters                           

  • Legal documents

  • Manuals/Handbooks/Brochures

  • Committee reports

  • Bulletins

  • Newsletters

  • Dissertations

  • Surveys, interviews & questionnaires 

  • Blogs/podcasts  

When can Grey Literature be useful?

  • It can help to reduce the effects of publication bias found with published research articles. For example, you can turn to the raw data from grey literature to obtain a more balanced view of the topic, as opposed to being potentially led by researchers to see a topic in a certain way. 

  • It can lead you to missed data, that may not have been indexed in the typical databases like Medline & CINAHL. For example, a search in clinicaltrials.gov  may guide you to trials that have not been indexed in these databases. 

  • It can lead you to the most up-to-date knowledge on a specific topic. For example, information from a conference paper is usually addressing the latest developments in a field. 

  • For some evidence including clinical, we need to go to grey literature to find the answers, like with statistical information.  

Where to find Grey Literature?

Grey Literature can be found in a variety of sources, from web sites, library catalogues, databases and repositories, as well as conducting a simple internet search using search engines. 

Some examples of where to go can be found below:

Web sites and Search engines 

To start, do a quick search using one of these search engines below:

Google Search https://www.google.com/

Google Scholar https://scholar.google.co.uk/

If not found, or for something more specific, take a look at one or more of these below:

King's Fund https://www.kingsfund.org.uk/publications 

The King's Fund's Information and Knowledge Services provide a unique and free source of information on health and social care policy and management. 

Nuffield Trust http://www.nuffieldtrust.org.uk/

Provides evidence-based research and policy analysis.

The Health Foundation http://www.health.org.uk/publications

Publications are available to download. Hard copies of many publications can also be ordered free of charge.

Grey Literature Report http://www.greylit.org/

Produced by the The New York Academy of Medicine between 1999 - 2016 Grey literature publications in "health services research and selected urban health topics". 

Gov.UK https://www.gov.uk/government/publications

Provides publications related to government. 

The National Archives http://www.nationalarchives.gov.uk/

The official archive and publisher for the UK Government, and for England and Wales.

MEDNAR (USA) http://mednar.com/mednar/desktop/en/search.html

Free, medically-focused deep web search engine.

CASH http://cash.libraryservices.nhs.uk/

A collaborative project provided by a network of librarians and knowledge managers in the health sector. 

UK Health Prevention First Forum http://ukhealthforum.org.uk/  

A UK health charity generating evidence to support policy change. 

Office for National Statistics (ONS) https://www.ons.gov.uk/

The UKs largest independent producer of official statistics. 

Library Catalogues

COPAC http://copac.jisc.ac.uk/

Brings together the catalogues of c.90 major UK and Irish libraries

British Library http://explore.bl.uk/

Search for theses, news media, reports and conferences. 

EThOS https://ethos.bl.uk/

Search up to 500,000 theses. 

Databases 

TRIP Database https://www.tripdatabase.com/

A clinical search engine designed to allow users to quickly and easily find and use high-quality research evidence to support their practice and/or care.

Many clinical trials are unpublished, making them 'Grey Literature'. 

Clinicaltrials.gov https://clinicaltrials.gov/

Explore 296,529 research studies in all 50 states and in 208 countries. 

UK Clinical Trials Gateway https://www.ukctg.nihr.ac.uk/

Find health and social care research here. 

WHO International Clinical Trials Registry Platform (ICTRP)  https://www.who.int/ictrp/en/

"Central database that harvests 16 primary clinical trial registries, including ANZCTR, ClinicalTrials.gov, EU Clinical Trials Register, and ISRCTN". 

Cochrane Library http://www.cochranelibrary.com/central

Search in Cochrane's Trials section for clincial trials. 

Other types of databases:

Proquest http://search.proquest.com/

Under this one search box you are searching six databases British Nursing Index (BNI), Hospital Premium Collection, Medline, PsycArticles & PsycINFO, and PTSDPubs. 

You can use the drop-down box to search for a variety of grey literature types, such as conference papers, dissertations, newspapers, trade journals, blogs and more. 

Social Science Research Network (SSRN) https://www.ssrn.com/en/

A global database of research in social sciences. 

North Grey Literature Collection Grey Literature related to health and public health in the North of England. 

Repositories 

BASE - https://www.base-search.net/

Provides access to more than 100 million documents from more than 5,000 sources.

OpenDoar  http://v2.sherpa.ac.uk/opendoar/

Directory of academic open access repositories

DOAJ (Directory of Open Access Journals)   https://doaj.org/

Access to high quality, open access, peer-reviewed journals

Core  https://core.ac.uk/

Access to millions of open access research papers

Worldcat   http://oaister.worldcat.org/

WorldCat is the world's largest library catalog, helping you find library materials online.

OATD (Open Access Theses and Dissertations) https://oatd.org/

A resource to find graduate theses and dissertations around the world. 

Last modified: Wednesday, 12 March 2025, 10:55 AM