Dakers, C. (1938) “Notes on Scottish Coins: (1) Rex Scottorum Pennies of David II.; (2) Edinburgh Light Groats of Robert III.; (3) Some James II. Groats of the Third Variety of the Fleur-de-lis Groats; and (4) Gilbert Kirkwood’s Mark on a Gold Coin of James V”, Proceedings of the Society of Antiquaries of Scotland, 72, pp. 122-128. doi: 10.9750/PSAS.072.122.128.