Columbia subject headings:
Gregorian chants--Instruction and study.
Music theory--Early works to 1800.
Harvard subject headings:
Gregorian chants--Instruction and study--Early works to 1800.
Gregorian chants--Instruction and study.
Manuscripts--Facsimiles
Music theory--History--500-1400--Early works to 1800.
Music--500-1400--Instruction and study--Early works to 1800.
Princeton subject headings:
Gregorian chants--Instruction and study--Early works to 1800.
Music--500-1400--Instruction and study--Early works to 1800.