Columbia subject headings:
Antiphons (Music)--History and criticism.
Catholic Church--Ambrosian rite.
Divine office (Music)--History and criticism.
Divine office--Liturgy--History.
Gregorian chants--History and criticism.
Harvard subject headings:
Antiphons (Music)--History and criticism.
Catholic Church--Ambrosian rite.
Divine office (Music)--History and criticism.
Divine office--Liturgy--History.
Gregorian chants--History and criticism.
Princeton subject headings: