Subject heading examples for music searching:
Printed music and recordings
Sonatas (Piano); String quintets (Violins (5); Operas; Toccatas; Brass music; Jazz--1981-1990; Rock music--Germany
Books about music
Jazz--History and criticism; Composers--Denmark--Biography; School music--Instruction and study; Music--19th century--Dictionaries
You can use a composer or performer's name as a subject to find materials about the person; use the name as an author to find compositions or recordings by the person
Library of Congress classification for music is primarily M
M and mM (miniature scores) - printed music in broad areas such as keyboard, string, wind, brass, percussion, other; arranged from one player to larger groups and then vocal music by genre (e.g. operas, musicals, songs, oratorios)
ML - music literature (books about music) including librettos, dictionaries, bibliographies, thematic catalogs, biographies, histories
MT - music theory, teaching, methods books on how to play instruments or learn singing