houghtonlib:Catholic Church. Graduale Fratrum Minorum secundum consuetudinem romane curie : manuscri
houghtonlib:Catholic Church. Graduale Fratrum Minorum secundum consuetudinem romane curie : manuscript, [ca. 1450-ca. 1500]. MS Typ 704.1 (13)Houghton Library, Harvard University -- source link
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