MLA

Church, Catholic. Processionale Praedicatorum. 0AD. https://collections.library.yale.edu/catalog/2077411.

APA, 6th edition

Church, C. (0 C.E.). Processionale praedicatorum [Early works to 1800, Manuscripts, Medieval Germany 15th century, Medieval and Renaissance Manuscripts in Beinecke Library]. https://collections.library.yale.edu/catalog/2077411.