Goldberg 2006, стр. 309 Goldberg, Eric Joseph (2006). Struggle for Empire: Kingship and Conflict under Louis the German, 817—876. Cornell University Press. ISBN978-0-8014-3890-5. OCLC60835308.
Goldberg 2006, стр. 310 Goldberg, Eric Joseph (2006). Struggle for Empire: Kingship and Conflict under Louis the German, 817—876. Cornell University Press. ISBN978-0-8014-3890-5. OCLC60835308.