^Secret Arms, The Saturday Review, London: Spottiswoode & Co., Vol. 77 No. 2,002 (10 March 1894), pp. 250-251
^Atkins, Anthony G., The Science and Engineering of Cutting: The Mechanics and Processes of Separating, Scratching, and Puncturing Bio-Materials, Metals, and Non-Metals, London: Elsevier Ltd., ISBN978-0-7506-8531-3 (2009), p. 214
^Ford, Roger, et al., Weapon: A Visual History of Arms and Armor, London: DK Publishing Inc., ISBN0-7566-2210-7, ISBN978-0-7566-2210-7 (2006), pp. 69, 131: In the late 1400s new blade shapes were introduced to the rondel dagger, an equilateral triangular cross-section, followed by the appearance of narrow square (cruciform) blades foreshadowing the emergence of the stiletto.