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LibrarySkills@UCL: Searching for information

A guide to search techniques and developing a search strategy for assignments, literature reviews and research.

What are subject headings?

A subject heading is like a tag, or a label, which describes what the item (book, article, etc.) is about. 

Subject headings are useful because they provide a consistent way of describing the subject matter of the item. When an item is added to a database, an indexer will decide which topics are covered by the article, and choose several subject headings to apply. 

The subject headings used are selected from a standardised list, or thesaurus; this is known as a ‘controlled vocabulary’. This means that all items about a particular subject would be tagged with the same, standard subject heading, regardless of the words and phrases the author used in the title or abstract. 

For example, let’s say you’re looking for articles about nosebleeds, so you search for nosebleed* in the title or abstract. 

PubMed search history showing 519 results for a search for nosebleed in the title or abstract

There are 519 articles with the word nosebleed or nosebleeds in the title or abstract. 

However if you search for the correct subject heading for nosebleed, which is epistaxis, you obtain far more results. (Note that in the screenshot MeSH stands for Medical Subject Headings)

screenshot of pubmed search history showing over 4000 results for epistaxis subject heading search

The principle does not only apply to medical terminology, of course. 

For example, if you wanted to look for articles about people who are trying to stop smoking, how would you search for that using textwords? ‘reduction in smoking’? ‘quit* cigarettes’? You might like to find a suitable subject heading such as Smoking Cessation, Smoking Reduction, or Tobacco Use Cessation 

This means that you should stand a better change of finding all items about that subject, even if the authors used words or phrases you didn’t think of. 

Subject headings are also really useful for finding items which don’t have an abstract, items in foreign languages, or items which have non-descriptive titles.

How do you search using subject headings? 

Find appropriate subject headings by searching in the subject heading field, or browsing the thesaurus, for the database you are using. Not all databases use subject headings, but those that do will each have their own unique thesaurus.   

Take a look at the explanation (sometimes called the ‘scope note’ ) for the heading if available, to make sure that the heading reflects the subject you are looking for. 

You can then search the database for all items tagged with that heading, and incorporate your subject heading search into your overall searching strategy.  Here is an example of how a simple search including subject headings might be constructed.

See our guides for specific resources for more help, or consult the help pages for the database you are using.

Important points to remember:

  • Not all databases use subject headings.
  • The thesaurus (list of subject headings) will be different for each database. For example, in Medline the subject heading for stereotyping is Stereotyping whilst in PsycINFO it is Stereotyped attitudes.
  • You should not rely on a subject heading search alone, but should combine it with a good text word search. This gives you the best chance of retrieving all relevant items. 
  • There will often be more than one subject heading which seems appropriate. Read the definition carefully, if available, to help decide which heading to use.
  • Another way to find the best subject heading to use is to have a look at which headings have been applied to articles you have already found.