Booleans are helpful when searching for information on a specific topic, such as ASL. The phrases "Deaf culture" and "American sign language" in quotation marks will return more specific results than the same phrases without quotation marks, for example.
Try this specialized linguistics database first.
Below are more general databases. Many of these are also searched by Discover@MU - if you are not finding what you want in a specific database, try searching there.
These are links to searches on subjects related to ASL and Deafness. You can use these as starting places to find books and other items within these subjects. You can also use the linked page to do your own subject searches.