Associated with long life, this Ushnishavijaya 33-Deity Mandala appears from the Kriyasamucchaya "text of Darpa Acharyia. The Tantric source text for this is the Vijaya-kalpa (rNam par rgyal ma'i rtog pa).
Compare to a mandala of similar size and finely executed detail in the Michael J. and Beata McCormick Collection, cf. D. Leidy and R. Thurman, Mandala: The Architecture of Enlightenment, 1997, pl. 25.