Beda, III: VI. «[Oswald] brought under his dominion all the nations and provinces of Britain, which are divided into four languages, viz. the Britons, the Picts, the Scots, and the English.» (EN) Beda il Venerabile, Ecclesiastical History of England III. URL consultato l'8 maggio 2011.
Jackson (1959), pp. 35-42; Smyth (1984), p. 31; Fraser (2009), p. 171. (EN) Kenneth Jackson, Edinburgh and the Anglian occupation of Lothian, in Clemoes (a cura di), The Anglo-Saxons: some aspects of their history and culture presented to Bruce Dickins, Londra, Bowes and Bowes, 1959, pp. 35–42. (EN) Alfred P. Smyth, Warlords and Holy Men: Scotland AD 80 – 1000, Edimburgo, Edinburgh University Press, 1984. (EN) James E. Fraser, From Caledonia to Pictland: Scotland to 795, Edimburgo, Edinburgh University Press, 2009, ISBN978-0-7486-1232-1.
Fraser (2009), pp. 201-202; Colgrave (1927), p. 41. «For in his early years, while the kingdom was still weak, the bestial tribes of the Picts had a fierce contempt for subjugation to the Saxon and threatened to throw off from themselves the yoke of slavery; they gathered together innumberable tribes from every nook and corner in the north, and as a swarm of ants in the summer sweeping from their hills heap up a mound to protect their tottering house.» (EN) James E. Fraser, From Caledonia to Pictland: Scotland to 795, Edimburgo, Edinburgh University Press, 2009, ISBN978-0-7486-1232-1. (EN) Bertram Colgrave, The Life of Bishop Wilfrid by Eddius Stephanus, Cambridge, Cambridge University Press, 1927, ISBN978-0-521-31387-2.
Colgrave (1927), pp. 41-43. «When King Ecgfrith heard this, lowly as he was among his own people and magnanimous towards his enemies, he forthwith got together a troop of horsemen, for he was no lover of belated operations; and trusting in God like Judas Maccabaeus and assisted by the brave sub-king, Beornhaeth, he attacked with his little band of God's people an enemy host which was vast and moreover concealed.» (EN) Bertram Colgrave, The Life of Bishop Wilfrid by Eddius Stephanus, Cambridge, Cambridge University Press, 1927, ISBN978-0-521-31387-2.