Costambeys, Marios; Innes, Matthew; MacLean, Simon (2011). The Carolingian World (بالإنجليزية). Cambridge University Press. p. 3. ISBN:978-0521563666. Archived from the original on 2021-09-27. Retrieved 2018-05-05.
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Costambeys, Marios; Innes, Matthew; MacLean, Simon (2011). The Carolingian World (بالإنجليزية). Cambridge University Press. p. 3. ISBN:978-0521563666. Archived from the original on 2021-09-27. Retrieved 2018-05-05.