Grey literature refers to research and information that is produced outside of traditional academic publishing channels. By its nature, grey literature is hard to locate and the content is of variable quality. Examples of grey literature include: theses, government reports, conference proceedings, research reports, newsletters, article pre-prints etc.
Some sources of grey literature are listed on this page, but please note this is not an exhaustive list.
Using grey literature in addition to published academic resources has many benefits:
Some sources of grey literature are listed below. Please note that this is not an exhaustive list.
Institutional Repositories
OpenDOAR (Directory of Open Access Repositories)
CORE: Aggregates research outputs from repositories worldwide
Individual university repositories eg QUB Research Portal
Preprint Servers
OSF (Open Science Framework): Hosts a wide range of research materials
Government & NGO Sources
United Nations Digital Library: Provides access to a wide range of UN-produced materials, including documents, publications, voting data etc
See Official Publications Subject Guide for more sources of government information
Conference Proceedings
Theses & Dissertations
ProQuest Dissertations & Theses Global: Collection of full-text dissertations and PhD theses from around the world, including from UK and Irish universities
Open Access Theses and Dissertations (OATD): International database giving free access to over 7 million theses and dissertations
Search Engines & Databases
BASE (Bielefeld Academic Search Engine): multilingual, multidisciplinary academic search engine that indexes over 300 million documents - 60% of which are open access.
Consider the following to decide if grey literature is of good enough quality to use in your review:
You may find it helpful to use an evaluation tool, such as the AACODS Checklist for appraising grey literature