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Systematic reviews - searching for literature: How to search databases (Part 1)

About databases

There are many different sorts of databases, but in this guide we are primarily concerned with databases that index academic journals. Databases may be subject specific, or multidisciplinary, but primarily what they do is add titles, abstracts and other information 'metadata' to the database. Sometimes they also add full text but that is very varied. To read more about which databases to search, look at the section What sources do I search?

How to search them

Databases usually offer keyword searching and some offer subject heading searching. It is necessary to understand the difference between the two. To be properly thorough, if a database offers subject headings, you will need to search with both keywords and subject headings.

Keyword searching. What is it?

Keyword searching is a very literal process. When you search using a word e.g. appendectomy, the database takes that word and looks through the data in each record for exactly that word. It would NOT however retrieve the record if they used the word appendectomies.

You should limit your search to the Title and Abstract fields as this makes your search replicable and also ensures a reasonable focus in the search.

Keyword search

Example record from Medline:


So to search more thoroughly with keywords you need operators like * which allow you to e.g. truncate. So a search for appendectom* would find articles where appendectomy OR appendectomies was used. This is explored further in the next section.

Keyword search operators

The operators described in this section can only be used with keyword searching and do not apply to subject heading searching.The most useful search operators used by the majority of databases (syntax e.g. a * for truncation, can very between suppliers) include:


E.g. nurs* . This will find nurse, nurses, nursing etc.

Proximity searching

A proximity indicator locates two words within a certain number of words of each other, either way around:

E.g. nurs* N3 role* . This will find  nurses role; nursing role; role of the nurse; roles of the nurse; roles of nurses etc.

Phrase searching

E.g. "nursing role" . This will only find the phrase nursing role, no variations.


E.g. Wom?n will find woman and women

To understand, for example, the particular value of say a proximity indicator, you need to begin to consider how someone may write something. The more you think about how a particular set of words might be phrased, the more you see the relevance of e.g. proximity indicators.

Subject heading searching

Subject heading searching is very different to keyword searching. The advantage of subject heading searching is that subject headings in databases already have articles attached to them irrespective of the terminology used in an article. This is useful as there are often multiple terms used for any given topic, or a topic is difficult to define using a given word e.g. 'adoption'. In social work, adoption, relating to a child, describes a very particular process, but the word used to describe it, adoption, can be used is multiple contexts. With a keyword search you will get lots of irrelevant results, but a search using a subject heading denoting the concept of adoption in social work, will only have articles attached to it where someone has actually reviewed the articles and considered them if relevant.

The example below demonstrates how to find and use a subject heading in a search (in this case using MeSH headings in the database Medline):



Once complete, the search will appear in your search history.


Databases with subject headings

  • Medline [MeSH]
  • PubMed [MeSH]
  • Cochrane [MeSH]
  • Embase [Emtree]
  • PsycINFO [PsycINFO headings]
  • CINAHL [CINAHL headings]
  • SocINDEX [Subject terms]
  • Academic Search Ultimate [Subject terms]
  • Business Source Ultimate [Thesarus]