Table 2 The order of literature search methods as presented in the guidance documents

1

Searching electronic databases

Searching bibliographic databases

Searching online literature databases and catalogues

Databases (development of search strategies, phase one)

Bibliographic databases (1.search for primary literature. 2. search for SRs)

Databases

Bibliographic databases

Bibliographic databases (1. subject databases. 2. general databases)

No list of search methods but guidance distinguishes between database searching (first) and supplementary searching (second)

2

Scanning references lists of relevant studies

Handsearching

Searching websites of organisations and professional networks

Database searching (phase two)

Search in trial registries

Grey literature

Study registries

Conference proceedings and meeting abstracts

3

Handsearching of key journals

Conference abstracts or proceedings

Searching the world-wide web

Review reference lists

Clinical practice guideline databases and providers

identifying on-going research

Searching for unpublished company documents

Existing review and publication reference lists

4

Searching trials registers

Other reviews

Searching bibliographies of key articles/ reviews

Handsearching

Requests to manufacturers

Theses

Regulatory documents

Web searching

5

Contacting experts and manufactures

Web-searching

Contacting key individuals who work in the area

Other data sources

Conference proceedings

Queries to authors

Unpublished studies

6

Searching relevant internet resources

Unpublished and on-going studies (inc. author contact)

Citation searches for key papers/ included papers

Citation searching

Further search techniques

On-going studies

7

Citation searching

Searching the web

Institutional repositories

8

Using a project website to canvas for studies

contact with experts

handsearching

9

Trials registers