Columbia subject headings:
Gregorian chants--Instruction and study--Early works to 1800.
Johannes, de Garlandia, active 13th century. De plana musica.
Music theory--Early works to 1800.
Musical intervals and scales--Early works to 1800.
Harvard subject headings:
Gregorian chants--Instruction and study--Early works to 1800.
Johannes, de Garlandia, active 13th century. De plana musica.
Music theory--Early works to 1800.
Music theory--History--500-1400.
Musical intervals and scales--Early works to 1800.
Princeton subject headings:
Gregorian chants--Instruction and study--Early works to 1800.
Johannes, de Garlandia, active 13th century. De plana musica.
Music theory--Early works to 1800.
Musical intervals and scales--Early works to 1800.