Columbia subject headings:
Music theory--History--500-1400.
Musical notation--History.
Harvard subject headings:
Music--500-1400--History and criticism
Musical meter and rhythm.
Musical notation--500-1400.
Princeton subject headings:
Music theory--History--500-1400.
Music theory--Mathematics.
Music--500-1400--History and criticism.
Music--500-1400--Philosophy and aesthetics.
Musical meter and rhythm.