y J. B. Benkard, Historical Sketch of the German Emperors and Kings (1855), p.2 ;
e.g.
Will Slatyer, Ebbs and Flows of Ancient Imperial Power, 3000 BC - 900 AD (2012), p. 323;
James, Edward (1988). The Franks. The Peoples of Europe. Oxford, UK; Cambridge, Massachusetts: Basil Blackwell. p. 232. ISBN0-631-17936-4.
Augustin Thierry, History of the Conquest of England by the Normans (1825), p. 55.