Searching systematically: literature searching in a systematic way

Your choice of database or information resource will depend on:

• Time available
• What resources you have access to
• Type of information you require
• What you need the information for
• Your area of expertise.

However, it is expected that more than one database will be searched.

Usually, you will start with a search of Medline (Ebsco/OVID/PubMed) and Embase.  Depending on your topic or area of interest, other databases should  be  searched, for example, CINAHL ( Nursing or Allied Health) or  PsycINFO ( Psychology or Mental Health).

Information is published in a variety of sources including:

1. Databases (Medline, CINAHL, PscyINFO, Embase, ERIC, Cochrane Library, Web of Science, etc.)
2. Books - print and e-books
3. Journals
4. Grey literature (Conference proceedings, Government Publications, Reports, Bulletins, Pamphlets, Dissertations)
5. Images/Film/Video
6. Social Media
7. Websites

Resources can consist of different types of information:

1. Clinical guidelines: NCEC (Ireland), (NICE (UK), WHO, 
2. Clinical Trials: Clinical Trials.gov (US), European Union Clinical Trials Register, ISRCTN registry
3. Systematic reviews : Cochrane Library, Campbell Collaboration

Some sources such as PubMed, Embase, Web of Science will provide access to a wide range of information types.  Others such as Cochrane Database of Systematic Reviews, trials registers, NICE Guidelines (UK) provide access to a specific type of information.

"Grey literature is usually understood to mean literature that is not formally published in sources such as books or journal articles" (Lefebvre et al. 2011, section 6.2.1.8) 

Hand searching is searching through medical journals or conference abstract proceedings for reports of research which are not indexed in the major electronic databases like MEDLINE and Embase.

Hand searching involves finding articles that cited a key article and also screening the reference lists of key articles.