Use Boolean Operators to connect terms in was that will affect the results of your search.
Boolean operators are:
AND will show you results for all of the keywords that you have included.
OR will show you results with any of the keywords you have used and will broaden the search:
NOT will eliminate certain keywords from your search, causing your results to narrow.
Other Useful Tips:
Quotation marks used before and after a phrase will force the database to search for the phrase rather than the individual word.
Use an asterisk (*) to broaden your search to find multiple keywords that start with the same letter.