Barrow, G.W.S. (2003): . Edinburgh University Press, Edinburgh, ISBN 0-7486-1803-1 Duncan, A.A.M. (2002): . Edinburgh University Press, Edinburgh, ISBN 0-7486-1626-8 Hudson, Benjamin T. (1996): . Greenwood Publishing Group, ISBN 0-313-29567-0 Oram, Richard (2004): . Tempus, Stroud, ISBN 0-7524-2825-X Orderic Vitalis: . Oversettelse fra 1853 av Thomas Forester, Francois Guizot, og Leopold Victor Delisle. Bind 3, s. 14.