Search for books with keywords. Once you've found a relevant book, scroll down to find the SUBJECT headings for more ideas. Here are some examples of Ethnomusicology subject headings:
Most of the resources you are looking for will fall in under "M" and "G" in Library of Congress Classification (how we organize the books). Here are some of the stack sections you may want to browse when looking for resources.
"M" classification can be found on Olin 3 and "G" classification can be found on Olin 2. Check the library map linked below or find a map posted next to all elevators in the library.