This handy music research guide will get you started: http://guides.library.upenn.edu/music. It points you to key sources for background research, finding books, journal articles, and streaming (digital) audio. If you would like a personalized research consultation please contact Music Liaison Librarian, Liza Vick (lizavick@upenn.edu). You can also visit her in the office adjacent to the Marian Anderson Study Center (Room 452.2) or schedule an appointment: https://libcal.library.upenn.edu/appointment/23416.