It is important to include grey literature into a systematic review in order to help minimize publication bias.
Grey literature includes documents produced by the government, academics, business and industry in both print and electronic formats where publishing is not the primary activity of the organization.
Grey literature examples:
- Conference abstracts
- Theses and dissertations
- Meeting records
- Reports (progress reports, annual reports)
- Government documents
- Newsletters and bulletins
- Standards and patents
- Toolkits, curriculums
- Lecture presentations and notes
Searching the grey literature can be overwhelming. It is recommended to search sources that are related to your research question. Start with searching for Abstracts and Conferences. If the question includes drugs and interventions, check pharma data and trial registries. Further, browse papers and reports of relevant stakeholder organizations. Below are some examples of where to search for grey literature.