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Table 1 Defining aspects and examples of ‘grey literature’, ‘grey data’, and ‘grey information’

From: Searching and synthesising ‘grey literature’ and ‘grey information’ in public health: critical reflections on three case studies

Term Defining aspect Examples
Grey literature [79] Not controlled by commercial publishing organisations Internal reports, Working papers, Newsletters
Grey data [12] User-generated, web-based Tweets, Blogs, Facebook status updates
Grey information Informally published or not published at all Meeting notes, Emails, Personal memories