Flechner, "Pope Gregory and the British" Histoires de Bretagnes 5, p. 47 [1]
wikisource.org
en.wikisource.org
Huddleston, Gilbert (1909). „Pope St. Gregory I ("the Great")”. Ур.: Herbermann, Charles. Catholic Encyclopedia. 6. New York: Robert Appleton Company. Gregory had come to be known as 'the Great' by the late ninth century, a title which is still applied to him. See John Moorhead, Gregory the Great, (Routledge, 2005), p. 1