* Mann, Horace K., "The Lives of the Popes in the Early Middle Ages, Volume 1: The Popes Under the Lombard Rule, from St Gregory I (the Great) to Leo III, Part 1" (London, 1912)==External links==
ISBN 0-500-01798-0* Mann, Horace K., The Lives of the Popes in the Early Middle Ages, Volume 1: The Popes Under the Lombard Rule, from St Gregory I (the Great) to Leo III, Part 1 (London, 1912)