Turner, J. W. Cecil (1964) [1962]. Kenny's Outlines of Criminal Law (18th ed.). Cambridge: Cambridge University Press. p. lvii.
St Clair Feilden, H.; Gray Etheridge, W. (1895). A Short Constitutional History of England (3rd ed.). B H Blackwell. Oxford. Simpkin, Marshall, Hamilton, Kent & Co. p. 335.