Table 1 Defining aspects and examples of ‘grey literature’, ‘grey data’, and ‘grey information’
| Term | Defining aspect | Examples |
|---|---|---|
| Grey literature [7–9] | 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 |