↑(en) Francis Clark, The "Gregorian" dialogues and the origins of Benedictine monasticism, Leyde (homonymie), BRILL, , 464p. (ISBN978-90-04-12849-1, lire en ligne)
↑(en) Alfred P. Smyth, «The Solar Eclipse of Wednesday 29 October AD 878: Ninth-Century Historical Records and the Findings of Modern Astronomy», dans Jane Annette Roberts, Janet Nelson et Malcolm Godden (éd.), Alfred the Wise: Studies in Honour of Janet Bately on the Occasion of Her Sixty-fifth Birthday, Boydell & Brewer, (ISBN9780859915151), p.190.