Columbia subject headings:
Harvard subject headings:
Choruses, Sacred (Mixed voices), Unaccompanied.
Gregorian chants.
Mary, Blessed Virgin, Saint--Songs and music.
Masses, Unaccompanied.
Motets.
Polyphonic chansons.
Princeton subject headings:
Masses, Unaccompanied.
Motets.
Polyphonic chansons.