De Coelesti Hierarchia
De Coelesti Hierarchia (Greek: Περὶ τῆς Οὐρανίας Ἱεραρχίας, translit. Peri tēs Ouranias Hierarchias, "On the Celestial Hierarchy") is a Pseudo-Dionysian work on angelology, written in Greek and dated to ca. AD the 5th century; it exerted great influence on scholasticism and treats at great length the hierarchies of angels.