Kirby (Earliest English Kings, p. 134) cites two documents: Birch CS 535 (Sawyer 209), and Sawyer 1782. The CS 535 text can be seen in the original Latin at "Anglo-Saxons.net: S 209". Retrieved 28 April 2007.. See also: F.M. Stenton(1970). Anglo-Saxon England. Oxford University Press; 3Rev Ed edition, 205. ISBN0-19-821716-1.
Lapidge, Michael; Godden, Malcolm; Keynes, Simon (22 June 2000). Anglo-Saxon England. Cambridge University Press. ISBN9780521652032 – via Google Books.