MUSCAT (Musselman Catalog) is the appropriate tool to find out whether or not Gettysburg College owns a particular item.
There are many different types of search you can perform:
Example: You want to find out whether or not Musselman Library has A Writer's Reference, by Diana Hacker on its shelves.
Note that you don't need to include the 'A' at the beginning of the title. MUSCAT ignores articles ("a", "an", and "the") as well as punctuation such as periods, colons, and apstrophes.
Type in the title of the book and click "Search" (or hit the Enter key).