1. Bernoulli, Daniel [28]. Letter to Goldbach, June 29, 1728. Correspondance Mathématique et Physique de quelques célèbres géomètres du XVIII siècle (Paul Heinrich von Fuss, editor), vol. 2 (1843), p. 262.
2. Brodetsky, S. A First Course in Nomography. G. Bell and Sons, London, 1925, pp. 129–133. The author gives nomographic solutions to ax = xb and related equations.