
If you want to focus or narrow your search results, click on the Advanced Search link on the left under the Browse and Search boxes.

The Advanced Search menu will open to give you options to search particular fields, date ranges, and collections.
You also can sort your results by relevance or publication date.

The green plus sign to the right of the search term box allows you to add another field to search with additional terms.

You can then choose a Boolean term to search for both terms to be in a resource (and), one or the other term to be in a resource (or),or to exclude resources with the term (not).