1984, Robert Silverberg, “Thomas the Proclaimer”, in Sailing to Byzantium, San Francisco, Calif.: Underwood–Miller; republished New York, N.Y.: IBooks, 2000, page 232
2014, Linda Safran, “Notes”, in The Medieval Salento: Art and Identity in Southern Italy (Middle Ages Series), Philadelphia, Pa.: University of Pennsylvania Press, page 373, footnote 14