1. M. Cantor, Vorlesungen über Geschichte der Mathematik, Leipzig, 1908, Vol. 3, pp. 214, 215, 786; Vol. 4, p. 508.
2. The Correspondence of Isaac Newton, ed. by H. W. Turnbull, Cambridge Univ. Press, New York, 1961, Vol. 3, pp. 148, 160, 329.
3. G. Loria, Spezielle algebraische und transzendente ebene Kurven, vol. II, Teubner, Leipzig, 1911.