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Library Services for Research

An overview of the services available via City's Libraries for Masters students, PhD students, postdoctoral and academic staff.

Advanced Search Techniques

An advanced literature search involves using a combination of Controlled Vocabulary/Subject Heading terms and free text/keyword searching.

# You should be aware that not all resources will allow you to search using Controlled Vocabulary/Subject Headings. If this is the case a free text/keyword search will suffice.

Controlled Vocabulary/Subject Heading searching involves searching for studies categorised under a given subject. Each study within a (relevant) database is categorised, according to the topic(s) it covers, these categorisations are its Subject Heading terms. An article about learning support in Universities, for example, would likely be given the Subject Headings 'Learning Support' or 'Student Support' and 'Universities' as these are the main areas which the article focuses on.

A Controlled Vocabulary/Subject Heading search is more precise than a free text/keyword search as it will retrieve results where the main focus of the study relates to the Subject terms that you enter. A free text/keyword search will retrieve results where your search terms are mentioned but the results may not focus on those terms.

Performing a Controlled Vocabulary/Subject Heading search

As with a free text/keyword search, you would need to search using subject terms for each concept of your search. For a topic on student experiences of learning support for study skills in Universities, for example, you would need to perform separate Subject Heading searches on student experiences, learning support, study skills and Universities.

Each Subject Heading search should be combined, using the Search History function, with a free text/keyword search relating to that concept. This search acts as a back up to the Subject Heading search as:

  • a study may have been categorised using a different subject term than the terms you used
  • a Subject Heading may have been mistakenly left out of the description of a study
  • a particular subject term may not exist in the database you are searching


A full search would thus look something like this in the Search History of a database:

Search 1 - (Subject search) for studies focussing on student experiences

Search 2- (Keyword search) for studies where terms relating to student experiences are mentioned

Search 3- Search 1 or Search 2 (combined)

Search 4- (Subject search) for studies focussing on learning support

Search 5- (Keyword search) for studies where terms relating to learning support are mentioned

Search 6- Search 4 or Search 5 (combined)

Search 7- (Subject search) for studies focussing on types of study skills

Search 8- (Keyword search) for studies where terms covering types of study skills are mentioned

Search 9- Search 7 or Search 8 (combined)

Search 10- (Subject search) for studies focussing on Universities

Search 11- (Keyword search) for studies where terms relating to Universities are mentioned

Search 12- Search 7 or Search 8 (combined)

You would be left with four searches covering each concept of your topic.These four searches would then be combined using the AND operator to retrieve your final result.


How you perform a Controlled Vocabulary/Subject Heading search will depend on the type of database you are using. Some databases have indexes/thesauri from which you can select your terms whilst others allow you to perform your search through a 'Field' search.

Using databases which have an index / thesaurus

If a database has an index/thesaurus you will need to enter your search term within this by selecting the appropriate button. Examples of databases which provide this function are available through the EBSCOhost platform.  For example, when using the Academic Search Complete or SOCIndex database you would select the Subject Terms button. When searching Art Full Text, Business Source Complete, PsycINFO or Political Science Complete you would select the Thesaurus button etc.

When searching an index/thesaurus you can only search one database at a time. You can also only enter one search term at a time.

On entering your search term the database will search it's index for the Subject term(s) available which relate most closely to your term.

(in some cases there may not be a relevant Subject term for the term you have entered. If this is the case search for a related term or perform a free text/keyword search for that term).

Clicking on the Subject term which is most relevant to your topic will take you into the index/thesaurus. Here, broader and narrower terms which relate to your topic will be listed. You can select as many as these as appropriate and perform your search. The searches for these Subject terms will be added to your Search History.

You can perform more than one Subject search for the same part of your topic. If there are other appropriate terms which did not come up in the index for your initial search, you can perform another search for these. Using the topic above, for example, you may need to perform separate Subject searches for study skills, essay writing, information literacy etc. 

Once all your Subject searches have been added to the Search History, you should then perform a free text/keyword search for that part of your topic. This will also be added to your Search History which will allow you to combine the two different searches together.

Using the Field option to search using Subject terms

Some databases will allow you to search using Subject terms by selecting an appropriate field. One example is the Web of Science database. Here you can enter all of the terms, which relate to one concept of your topic, in the search bar. From the 'field' menu you can then select the Subject field (in the case of Web of Science this is the 'Topic' field).

The database will then retrieve all results which have been categorised under the terms you have entered. These will be added to your Search History.

You should repeat the search using the same terms in the Abstract field (or in the case of Web of Science the 'Title' field). Your results will again be added to your Search History where you can combine the two searches together.

Searching for specific types of information

There are different types of information you may need to find for your research other than relevant literature. You may, for example, need to find business or economic data.

For this type of information you should refer to your Subject Guide.