Coba jelasin Sumber dari Grimoaldo III dari Benevento dong

Gwatkin, H. M., Whitney, J. P. (edd.) The Cambridge Medieval History: Volume II—The Rise of the Saracens and the Foundations of the Western Empire. Cambridge: Cambridge University Press, 1926.

Oman, Charles. The Dark Ages 476-918. London: Rivingtons, 1914.

Hodgkin, Thomas. Italy and her Invaders. Oxford: Clarendon Press, 1895.

McKitterick, Rosamond. The Frankish Kingdoms under the Carolingians, 751–987. London: Longman, 1983. ISBN 0-582-49005-7.