Solo songs with orchestra
M 1613 - Full scores
M 1614 - Vocal scores
Solo songs with piano
M 1600 - M 1990's - various collections of songs, folk-songs, etc.
M 1619 - Collections by more than one composer
M 1620 - Collections by one compoers:
M 1620.B - Brahms
M 1620.F - Faure
M 1620.I - Ives
M 1620.S - Schubert, Schumann, Strauss
M 1621 - Separate songs
M 1621.4 - Song Cycles
Operas, musical
M 1500 - Full scores
M 1503 - Vocal scores
M 1507 - Operatic anthologies
M 1508 - Selections from musicals, operas
Oratorios
M 2000 - Full scores
M 2003 - Vocal scores
Other useful numbers
M 1530 - Secular choruses, mixed voices with orchestra, full scores
M 1533 - Secular choruses, mixed voices with orchestra, vocal scores
M 2010 - Masses
M 2011 - Masses, unaccompanied
M 2020 - Sacred choruses, mixed voices with orchestra, full scores
M 2023 - Sacred choruses, mixed voices with orchestra, vocal scores
Literature (a selective list)
ML 46 - ML 54.8 - Librettos, Scenarios (includes operas, oratorios, art songs, etc.)
ML 102 .06 - Opera dictionaries, encyclopedias (most in "reference")
ML 410 - Composer biographies
ML 420 - Singer biographies
ML 1400 - ML 3275 - Vocal music
ML 1460 - Vocal technique
ML 1500 - ML 1554 - Choral music
ML 1600 - ML 2881 - Secular vocal music
ML 1700 - Dramatic music (opera, musical theatre, etc.):
ML 1711 - United States
ML 1727 - France
ML 1729 - Germany
ML 1731 - British Isles
ML 1733 - Italy
ML 2500 - ML 2862 - Songs
ML 2600 - ML2770 - Part songs
ML 2633 - Madrigals
ML 2800 - ML 2862 - Solo songs:
ML 2811 - United States
ML 2827 - France
ML 2829 - Germany (Lied)
ML 2831 - British Isles
ML 2900 - ML 3275 - Sacred vocal music:
ML 3000 - Christian (general)
ML 3002 - ML 3095 - Roman Catholic
ML 3100 - ML 3188 - Protestant
ML 3195 - Jewish
ML 3197 - Islamic
Instruction and study:
MT 820 - General singing and voice culture
MT 821 - Physiology, hygiene
MT 823 - History of vocal pedagogy
MT 825 - MT 850 - Systems and methods
MT 883 - Pronunciations, diction, etc.
MT 885 - Studies and exercises