Grey Literature
What is it ? Grey Literature includes things like reports, newsletters, conference proceedings abstracts, guidelines, research and technical reports, working papers, theses and dissertations, government documents, clinical trials and ongoing research registries, standards and patents, newsletters and bulletins, powerpoint presentations, data sets, social media posts, film/video, audio, newspapers, email, discussions lists and forums or basically anything that isn't commercially published.
Why use it?
Sometimes traditionally published data doesn't give you a complete view of a topic from all sides.
Sometimes information and evidence may only be available at a very local level. If you rely on published resources only they may not give the full picture of a subject, situation or treatment.
Where can it be found? Unfortunately, it is not all in one place. Sometimes it can be found in databases but not always. The following links may help.
| Databases of Grey Literature | Open Grey sources of grey literature in Europe |
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Grey Source from Grey Net International which focusses on Research, Publication, Open Access, and Education in the field of Grey Literature. |
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| Clinical Trials Registers | ICTRP - International Clinical Trials Registry Platform from the WHO |
| Clinical Trials.gov - database of privately and publicly funded clinical studies conducted around the world. | |
| EU Clinical Trials Register - | |
| Institutional Repositories | CORE |
| OpenDoar | |
| BASE | |
| Prospero | |
| TRIP - Turning Research into Practice | |
| Dissertations | PDQT Open - Proquest Open Access Dissertations and Theses |
| OATD - Open Access Theses and Dissertations | |
| eTHOS - e-theses online service | |
| Tweets | Twitter advanced search |
| Greylitnet | |
| Greylitnet - discover research | |
| UK Non-Governmental Insitutions | King's Fund - health and social care policy and management |
| Nuffield Trust - evidence based research and policy analysis | |
| The Health Foundation | |
| Charity Choice | |
| Advance Google and Other Search Engines | |
| Acknowledgements | This information is based on a presentation by Jo Hooper UH Bristol Foundation Trust and a user guide by Isla Kuhn Cambridge University Medical Library. |
You will need to assess the quality of the information you find.
Use the AACODS checklist which helps with the evaluation and critical appraisal of grey literature.
Check out our Critical Appraisal and Critical Thinking pages.
See the links below which demonstrate why searches for unpublished data and grey literature, particularly when carrying out systematic reviews, are important in finding the evidence. Searching bibliographic databases only, may not give a complete view of a situation or treatment.