You can focus or narrow your search results by using the search limits or search refinements provided by the database.
These refinements can be applied before your keyword search (on the Basic or Advanced Search pages) or after your keyword search (in a "Refine Results" or "Filter Results" area next to your search results).
Best practice is to apply any search limits AFTER your initial search. This way you can see how many results you have to work with, then narrow your search by applying one limit at a time.
Search Limits in Academic Search Premier
Search Limits in Academic OneFile (Gale)