Sekundære kilder Hunter Blair, Peter (1960): . Cambridge: Cambridge University Press. (2003 edition: ISBN 0-521-83085-0) Hunter Blair, Peter (1966): . W.W. Norton & Company. ISBN 0-393-00361-2. Campbell, James; John, Eric & Wormald, Patrick (1991): . London: Penguin Books. ISBN 0-14-014395-5. Fletcher, Richard (1989): . London: Shepheard-Walwyn. ISBN 0-85683-089-5. Hill, David; Margaret Worthington (2005): . British Archaeological Reports, British series, 383. Oxford: Archaeopress. ISBN 1-84171-687-1. Kirby, D.P. (1992): . London: Routledge. ISBN 0-415-09086-5. Stenton, Frank M. (1971): . Oxford: Clarendon Press. ISBN 0-19-821716-1.