Finding Music Books

Library of Congress Subject Headings (LCHS):

Choir
Music
Opera
Conducting
Instrumentation
Score

You may want to browse these call ranges:

780 Music
781 General principles & musical forms
782 Vocal music
783 Music for single voices The voice
784 Instruments & Instrumental ensembles

785 Chamber music
786 Keyboard & other instruments
787 Stringed instruments (Chordophones)
788 Wind instruments (Aerophones)