Thomson 1991. Thomson, Robert W. (1991). "Agathangelos". In Kazhdan, Alexander (ed.). The Oxford Dictionary of Byzantium. Oxford and New York: Oxford University Press. ISBN0-19-504652-8.
One or more of the preceding sentences incorporates text from a publication now in the public domain: Herbermann, Charles, ed. (1913). "Agathangelus". Catholic Encyclopedia. New York: Robert Appleton Company.