Cantus: A Database for Latin Ecclesiastical Chant - Inventories of Chant Sources | Cantus Manuscript Database https://cantus.uwaterloo.ca/
"Cantus is a database of the Latin chants found in manuscripts and early printed books, primarily from medieval Europe. This searchable digital archive holds inventories of antiphoners and breviaries -- the main sources for the music sung in the Latin liturgical Office -- as well as graduals and other sources for music of the Mass."