Unlike searching in Google, library research relies heavily on the use of "keywords" - the words you enter into a search box. Since one author may use different words than another to discuss the same topic, you will want to brainstorm synonyms for important words, and conduct multiple searches.
Keep in mind that the words you use will influence the search results. For example, each of the following searches will yield different results:
When exploring resources, then, trying different phrases can help you see different perspectives on the same topic.
Additionally, conducting multiple searches with synonyms can help you find additional sources that one search alone might not reveal. For example, with a topic like laws, you might want to try words like regulations, statutes, or legislation. You can then conduct multiple searches, such as: