Columbia subject headings:
Processionals (Liturgical books)--Bibliography--Catalogs.
Rituals (Liturgical books)--Bibliography--Catalogs.
Harvard subject headings:
Music--Manuscripts--Catalogs
Processionals (Liturgical books)--Bibliography--Catalogs.
Rituals (Liturgical books)--Bibliography--Catalogs.
Princeton subject headings:
Catalogs.
Catholic Church--Liturgy--Manuscripts--Catalogs.
Gregorian chants--Europe--Catalogs.
Music--Manuscripts--Europe--Catalogs.
Processionals (Liturgical books)--Europe--Catalogs.