Rogers, 2010, p. 51. Rogers, Clifford J (2010). The Oxford encyclopedia of medieval warfare and military technology. New York: Oxford University Press. ISBN978-0-19-533403-6. OCLC890690604.
Flodoard, 1839, p. 373. Flodoard (1839). «Flodoardi Annales.». Monvmenta Germaniae historica ... avspiciis Societatis aperiendis fontibvs rervm germanicarvm medii aevi, edidit Georgivs Heinricvs Pertz ... OCLC26138984.
Rogers, 2010, p. 52. Rogers, Clifford J (2010). The Oxford encyclopedia of medieval warfare and military technology. New York: Oxford University Press. ISBN978-0-19-533403-6. OCLC890690604.