Meyer, Kuno (1896), "Early Relations Between Gael and Brython", in Evans, E. Vincent (ed.), Transactions of the Honourable Society of Cymmrodorion, Session 1895–1896, vol. I, London: Honourable Society of Cymmrodorion, pp. 55–86
Mommsen, Theodor (1885), "Britain", The Provinces of the Roman Empire, vol. I, translated by Dickson, William P., New York: Charles Scribner's Sons (published 1887), p. 211