Aquilla Smith, « On the Irish Coins of Edward the Fourth », Transactions of the Royal Irish Academy, Dublin, Royal Irish Academy, vol. 19, , p. 31–33 (lire en ligne)
(en-GB) William Gordon Perrin, British Flags : Their Early History and their Development at Sea; With an Account of the Origin of the Flag as a National Device, Cambridge University Press, (1re éd. 1922) (ISBN978-1-107-64935-4 et 1-107-64935-8, OCLC755072151, lire en ligne)