The types of sources you choose depends on the topic of your review. Typically, these will be databases and they will be relevant to your subject area. Find out what each of the databases cover - you will be expected to know this! Also, some databases use a controlled vocabulary (subject headings) to help you search and some use keyword searching. You need to know which uses which to search them properly. For more information on controlled vocabularies - see the box to the right.

Database resources

Nearly all subject areas can use the multi-disciplinary databases Scopus and Web of Science - these cover all the subject areas and are keyword databases so they only search for the terms you put in - this is why your list of synonyms is important.

You will then need to look at the subject databases in your discipline area.

Most systematic reviews are carried out in the field of medical sciences. For this the following databases would be used:

Medline - covers medical sciences including dentistry from 1946 to current.

Embase - clinical medical sciences with emphasis on drug and drug therapy from 1980 to current.

PsycInfo - psychology, psychiatry and behavioural sciences database with coverage from 1806.

Cochrane Library - databases of systematic reviews carried out in the field of clinical sciences.

HMIC - database of health service policy, management and administration from 1979.

CINAHL - material on nursing and allied health professions. Covers 1981 to present.

There are also a number of other specialist databases which might be appropriate to use.

For information on databases relevant to your subject area, look here: http://www.ncl.ac.uk/library/subject-support/

Non-database resources

You may want to look at Grey Literature which tends to be government, organisation, industry or commercial material which is usually (but not always) published for non-academic purposes. These are normally reports, theses or conference proceedings.

For information on grey literature, see the categories on the subject support pages here: http://www.ncl.ac.uk/library/resources/

Controlled vocabularies are used to ensure that searches retrieve all relevant results even when the authors use different terms. In the example below, we can use the term 'dogs' instead of individual names of breeds and all the articles on dogs will be retrieved regardless of the breed or the term which the author used in their article.

Different databases use different languages and usually guide or suggest the appropriate terms to you when you enter your search term.

Examples of controlled vocabularies:

ERIC (education database) uses Thesaurus of ERIC descriptors

PsycInfo uses American Psychological Association Thesaurus

Medline used MeSH (Medical Subject Headings).