For each main concept, list alternative terms, including synonyms and singular and plural forms of the words. Sometimes synonyms, plurals, and singulars aren’t enough. So also consider associations with other words and concepts. For instance, it might help, when looking for information on the common cold, to include the term virus—because a type of virus causes the common cold. Check to make sure that your terms are not too broad or too narrow for what you want. Figuring out what’s too broad or too narrow takes practice and may differ a bit with each search.
Tip: Try a Thesaurus
Subject Headings Instead of Keywords
All the searches we have talked about so far have been keyword searches, usually used in search engines. But it really pays to use tools—such as library catalogs and journal article databases—that have subject headings that you can search. Subject headings are standardized terms that are assigned by trained experts. Some such tools also allow keyword searching. See the section on Specialized Databases for more detail about searching subject headings.