Keep track of the words that are used to describe your topic. This will help you when you are searching in different databases, because not every author uses the same keywords to describe the same topic.
What were the important words you found in the encyclopedia?
Are there synonyms for these words? Example: "heart disease" and "cardiovascular disease"
Are there broader (less specific) or narrower (more specific) words you could use? Example: "Smog" is more specific than "air pollution," but "children" is less specific than "kindergartners."
Not every database or article uses the same words to describe the same topic, so look for suggested keywords or subject terms during your search.