Frank Barlow, The Feudal Kingdom of England 1042-1216, David MacKay Company, 1961. John Cannon, The Oxford illustrated history of the British monarchy, Oxford
Frank Barlow, The Feudal Kingdom of England 1042-1216, David MacKay Company, 1961. John Cannon, The Oxford illustrated history of the British monarchy, Oxford
Frank Barlow, The Feudal Kingdom of England 1042-1216, David MacKay Company, 1961. John Cannon, The Oxford illustrated history of the British monarchy, Oxford
; Tucker, Spencer C. The Big Guns: Civil War Siege, Seacoast, and Naval Cannon. Alexandria Bay, New York: Museum Restoration Service. ISBN 0-88855-012-X