What theory are you using?
What are other terms for your theory? These can mean the same thing or be similar. Theories evolve over time as different experts study and use them.
Keep track of what search terms you use. Try out different terms in multiple databases. Databases are listed in the AN 470 Articles Page.
Databases do not understand questions like Google can.
Databases talk through search queries.
Search queries are combinations of search terms, Boolean Operators, and punctuation.
Turn your research question into search terms.
Look at that article's keywords. Keywords are usually written underneath the article's listing in your search results.
Different databases use different keywords. By reusing the keywords, you are learning to speak that database's "language".
Some databases will give you suggestions for search terms when you start typing in a search box. These are terms that the database absolutely recognizes.
Sometimes, the suggestions will be several terms in the same text box, all separated by the Boolean Operator or. This means that the search engine will search for all those terms at once.
Always check before you select a string of terms. Some of the terms might not be equivalent for your specific research topic!