"Grey literature stands for manifold document types produced on all levels of government, academia, business and industry in print and electronic formats that are protected by intellectual property rights, of sufficient quality to be collected and preserved by libraries and institutional repositories, but not controlled by commercial publishers, i.e.where publishing is not the primary activity of the producing body.” (International Conference on Grey Literature, 2010).
It is sometimes referred to as ephemeral, fringe, gray or fugitive literature.
Lacks editorial polish
Not conventionally published
May be made publically available or distributed privately
Different bodies produce grey literature, including the University and you. It is produced by the medical sciences, business and social sciences, all levels of government and industry in print and electronic formats. Here are some additional examples:
Looking for unpublished material is a good way to counteract publication bias and include a broader scope of the literature. However, grey literature has not been through any peer review process and needs to be carefully evaluated. Flinders University have created the AACOD checklist to enable evaluation and critical appraisal of grey literature:
Benefits of including grey literature in the review process include:
It can be tricky to find grey literature because traditionally there were no central sources such as libraries or databases where it would be collected. It is not systematically described, organised or indexed. Neither has it gone through a formal peer-reviewing process and it has been argued that for this reason grey literature should not be included in systematic reviews.
It can be harder and more time-consuming to identify relevance in the title and abstract stage of a review as citation information or abstracts may not exist and it does not conform to a specified format (abstract, methods, results, discussion) as peer-reviewed literature does.
Examples of where to search for grey literature:
Google Scholar advanced search – academic material
Google advanced search - general search