You can reduce the number of items that are returned in your search results based on several different fields. Click one or more options on the left side of the search results page to refine your results. Choices include options for availability, found in, format, collection, location, and more.
Your current refinements will be listed at the top of the sidebar. If you decide you want to undo one of your choices, click the (x) to the right of the selected option.