Menger, Karl (1926), "Allgemeine Räume und Cartesische Räume. I.", Communications to the Amsterdam Academy of Sciences. English translation reprinted in Edgar, Gerald A., ed. (2004), Classics on fractals, Studies in Nonlinearity, Westview Press. Advanced Book Program, Boulder, CO, ISBN978-0-8133-4153-8, MR2049443
Quinn, John R. (2013). "Applications of the contraction mapping principle". In Carfì, David; Lapidus, Michel L.; Pearse, Erin P. J.; van Frankenhuijsen, Machiel (eds.). Fractal geometry and dynamical systems in pure and applied mathematics. II. Fractals in applied mathematics. Contemporary Mathematics. Vol. 601. Providence, Rhode Island: American Mathematical Society. pp. 345–358. doi:10.1090/conm/601/11957. ISBN978-0-8218-9148-3. MR3203870.. See Example 2, p. 351.
Quinn, John R. (2013). "Applications of the contraction mapping principle". In Carfì, David; Lapidus, Michel L.; Pearse, Erin P. J.; van Frankenhuijsen, Machiel (eds.). Fractal geometry and dynamical systems in pure and applied mathematics. II. Fractals in applied mathematics. Contemporary Mathematics. Vol. 601. Providence, Rhode Island: American Mathematical Society. pp. 345–358. doi:10.1090/conm/601/11957. ISBN978-0-8218-9148-3. MR3203870.. See Example 2, p. 351.
Quinn, John R. (2013). "Applications of the contraction mapping principle". In Carfì, David; Lapidus, Michel L.; Pearse, Erin P. J.; van Frankenhuijsen, Machiel (eds.). Fractal geometry and dynamical systems in pure and applied mathematics. II. Fractals in applied mathematics. Contemporary Mathematics. Vol. 601. Providence, Rhode Island: American Mathematical Society. pp. 345–358. doi:10.1090/conm/601/11957. ISBN978-0-8218-9148-3. MR3203870.. See Example 2, p. 351.