MLA

Lenon, Romain. Commonplace Book. 0AD. https://collections.library.yale.edu/catalog/11150269.

APA, 6th edition

Lenon, R. (0 C.E.). Commonplace book [Manuscripts, Medieval France 15th century, Medieval and Renaissance Manuscripts in Beinecke Library]. https://collections.library.yale.edu/catalog/11150269.