MLA

Pseudo-Dionysius, the Areopagite. De Caelesti Hierarchia. 0AD. https://collections.library.yale.edu/catalog/15949761.

APA, 6th edition

Pseudo-Dionysius, the A. (0 C.E.). De caelesti hierarchia [Translations, Manuscripts, Medieval France 14th century, Medieval and Renaissance Manuscript Fragments in Beinecke Library, Medieval and Renaissance Manuscripts in Beinecke Library]. https://collections.library.yale.edu/catalog/15949761.