Columbia subject headings:
Church music--Catholic Church--15th century.
Church music--Catholic Church.
Gloria in excelsis Deo (Music)--History and criticism.
Tropes (Music)--History and criticism.
Harvard subject headings:
Church music--Catholic Church--15th century.
Church music--Catholic Church--500-1400.
Gloria in excelsis Deo (Music)--History and criticism.
Spiritus et alme (Music)
Tropes (Music)--History and criticism.
Princeton subject headings:
Tropes (Music)