From the library homepage, or the CentralSearch box located further up on this LibGuide, type in your search terms:
You will arrive at a results page.
On the left hand side of the page, in the column called "Refine my Results" you will see the different options you can choose to narrow your search. In this case, we will choose "scores" under the section "Resource Type". On this list, there are 95 music scores that are related to the search term "Mahler" and that are currently available in the lirbary:
Each entry will indicate to you whether or not the music score is available to check out: