Columbia subject headings:
Songs with piano.
Vocal duets with piano.
Vocal quartets, Unaccompanied.
Harvard subject headings:
Scores
Songs
Songs with piano
Vocal duets with piano
Vocal quartets, Unaccompanied
Princeton subject headings:
Scores.
Songs with piano.
Songs.
Vocal duets with piano--Scores.
Vocal quartets, Unaccompanied--Scores.