1. In Mathesis, vol. 9 (1889), p. 75 and p. 110. In the latter note the case of the two functionsx 2 andx·?x? is cited as an illustration. Further examples have been given by Bôcher in the articles hereafter cited. Peano has another paper on the same subject in the Rendiconti della R. Accademia dei Lincei, ser. 5, vol. 6, 10 sem. (1897), p. 413.
2. See also Bulletin of the American Mathematical Society, ser. 2, vol. 7 (1900), p. 120, and Annals of Mathematics, ser. 2, vol. 2 (1901), p 93. The properties of Wronskians of functions of a real variable have been further investigated by the same writer in the Bulletin of the American Mathematical Society, ser. 2, vol. 8 (1901), p. 53.
3. Cf. Bôcher, l. c., pp. 141, 142.
4. Cf. formula (4), p. 287.
5. Cf. E. Pascal, Die Determinanten (translation by Leitzmann), p. 39.