Charles Cawley: Medieval Lands. Dostupné online. [cit. 2016-03-06].
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NELSON, Janet L. King and Emperor: A New Life of Charlemagne. [s.l.]: Univ of California Press Dostupné online. ISBN978-0-520-31420-7. (anglicky)
SMITH, William; WACE, Henry. A Dictionary of Christian Biography, Literature, Sects and Doctrines; Being a Continuation of 'The Dictionary of the Bible'. [s.l.]: J. Murray, 1877. Dostupné online. (anglicky)
CORRADINI, Richard; DIESENBERGER, Maximilian; REIMITZ, Helmut. The Construction of Communities in the Early Middle Ages: Texts, Resources and Artefacts. [s.l.]: BRILL, 2003. Dostupné online. ISBN978-90-04-11862-1. S. 417. (anglicky)
FOURACRE, Paul; GANZ, David. Frankland: The Franks and the world of the early middle ages. [s.l.]: Manchester University Press 360 s. Dostupné online. ISBN978-1-5261-4825-4. (anglicky)