Keyword and subject terms searching can be combined. For example, rather than guessing what keywords to use consider doing a thesaurus (controlled vocabulary) search first. Review and assess your results. Then, add a keyword search to the query or use Search History to combine searches.

Identify all the major concepts of your thesis or research topic. Then use the thesaurus or subject index to locate, explore and select subjects (also known as descriptors) for each concept of your topic.

Unlike common keyword searches, which are based on exact word matches, subject or thesaurus searches retrieve records based on assigned subject headings or descriptors.

Subject headings, descriptors, and thesauri terms are examples of controlled vocabularies--pre-defined, carefully selected words and phrases used to classify and organize information. Controlled vocabulary describes the overall content of an information unit, such as a book, article, or essay. Searching with controlled vocabulary in a subject index or thesaurus allows for more precise results, reveals relationships between related terms, and helps identify synonyms as well s broader and narrower terms.

Use subject headings and thesauri to:

• get ideas
• browse related, broader and narrower topics of interest
• get specific, targeted results
• combine with keyword searching for more focused results

Subject headings and thesauri terms vary by discipline and database. For example, ATLA Religion database includes a Scripture search, while APA PsycInfo uses the APA Thesaurus of Psychological Index Terms.

Below are several examples of databases and the controlled vocabulary they use: