I have a list of results. How do I further narrow that list down to sources I might use?
The best way to do that is to read the whole article or book. However, during the research process, there isn’t always time to do that. Whenever possible, you should take advantage of tools such as subject headings/descriptors and abstract.
A subject heading (sometimes known as a descriptor) is a standardized term, usually a word or a phrase used to describe what the article or book is about. There are usually several subject headings per book or article. Subject headings exist in order to organize a collection of information. Consider using subject headings you find as search terms.
An abstract is a short summary of what the article or book is about.
Other tools for books you should use are a table of contents and the index once you find the book on shelf.