Use BU Libraries Search which includes deep, full-text searches through many--though not all--publications accessible in our libraries.
The BULS search also pulls performing arts-related titles you may already have in mind,
but with subject-special databases, so much else can be discovered, too:
and continue in interdisciplinary directions
Open stack ranges for book browsing include:
MT 955-956 production and staging; performance skills, preparation
ML 1707-2054 general and also specific works on opera, music theater
These open access portals link you to digital representations of original source material.