^Charles Reginald Haines, Dover Priory: A history of the priory of St Mary the Virgin, and St Martin of the New Work, (Cambridge University Press, 1930), p.20: "we know for certain that Ethelberht,King of Kent (550-616), about the year 573 married a Christian wife, the Frankish princess Bertha or Aldeberga"
Law-code of Æthelberht, ed. and tr. F. Liebermann, Die Gesetze der Angelsachsen. 3 vols. Halle, 1898–1916: 3–8 (vol 1); ed. and tr. L. Oliver, The Beginnings of English Law. Toronto Medieval Texts and Translations. Toronto, 2002.
Letters of Gregory the Great, ed. D. Norberg, S. Gregorii magni registrum epistularum. 2 vols. Turnhout, 1982; tr. J.R.C. Martyn, The letters of Gregory the Great. 3 vols. Toronto, 2004.
Earliest vita of Gregory the Great, ed. and tr. Bertram Colgrave, The earliest life of Gregory the Great by an anonymous monk of Whitby. Lawrence, 1968.
Blackburn, Mark & Grierson, Philip, Medieval European Coinage. Cambridge: Cambridge University Press, reprinted with corrections 2006. ISBN0-521-03177-X