Columbia subject headings:
Graduals (Liturgical books)
Gregorian chants.
Music--England--York--15th century.
Music--Manuscripts--Facsimiles.
Harvard subject headings:
Gregorian chants.
Masses, Unaccompanied.
Music--Manuscripts--Facsimiles
Princeton subject headings:
Chants.
Graduals (Liturgical books)
Gregorian chants.
Music--England--York--15th century.
Music--Manuscripts--Facsimiles.