Grey literature refers to a wide range of publications that are not books or journal articles
Grey literature should be included in a thorough or systematic review of the literature as it can:
- Reduce positive publication bias
- Provide a wider range of information, especially from those who do not publish in academic journals (Practitioners, industrialists, victims, patients)
- Have a strong local or regional flavour
- Present government or other official policies
- May be more detailed than conventional books or articles
Grey literature includes:
- Discussion papers, Working papers
- Theses and dissertations
- Protocols and guidelines
- Clinical trials
- Market reports
- Government documents, White papers
- Conference posters and presentations
- Statistical resources
- Standards, patents, technical specifications
Social media such as Twitter or Facebook might also be classed as a form of grey literature.
Finding reports, discussion papers and working papers
General sources of grey literature include:
- OpenGrey - a multidisciplinary European database for "grey literature"
- BASE - the Bielefeld Academic Search Engine
- Union catalogues such as Library Hub Discover or WorldCat include reports and theses
You can search institutional repositories through services such as OpenDOAR
Another technique for finding reports is citation pearl searching – search Google Scholar for a key paper in your area and see the publications which have cited it – there may well be reports as well as journal articles.
Investigate people’s websites
People who are working in your field are a good source of grey literature. Start from their institutional webpages and check out their publication lists, where you may find reports alongside articles and books. Current activities/projects pages may also include grey literature. You may also be able to follow them on Twitter, Facebook, LinkedIn and other social media sites.
As your work progresses, you’ll become aware of the main organisations active in your field – charities, pressure groups, learned societies, government bodies, research institutes. Do a thorough search of their webpages.
Evaluating grey literature
Grey literature has not been through any sort of peer review process. Therefore it is particularly important that you evaluate material very carefully to decide whether to use it.
The AACODS checklist is designed to enable evaluation and critical appraisal of grey literature:
- A Authority
- A Accuracy
- C Coverage
- O Objectivity
- D Date
- S Significance
It was prepared at Flinders University and there is a very helpful annotated checklist.