^David Charles Douglas. Time and the hour: some collected papers of David C. Douglas. Eyre Methuen, 1977. p. 138–139
^Bernard S. Bachrach & Steven Fanning. The Annals of Flodoard of Reims, 919-966. Volume 9 of Readings in medieval civilizations and cultures. University of Toronto Press, 2004. Chapter 2 (The events in Flodoard's Annals).
^Richard Huscroft. Making England, 796-1042. Routledge, 2018. Chapter 2: Ruling the kingdoms 796-899.