1. Alexanderson, G. L. (interviewer). 1985. “George Pólya,” in: Mathematical People: Profiles and Interviews, (Donald J. Albers and G. L. Alexanderson, eds.), Boston: Birkhäuser, pp. 246–253; see p. 250.
2. Bell, E. T. 1937. Men of Mathematics, New York: Simon and Schuster. Includes lively semipopular accounts of the Bernoullis, Euler, and Fermat.
3. Bellman, Richard. 1947. “A Note on Relatively Prime Sequences,” Bull. Am. Math. Soc. 53: 778–779.
4. Calinger, Ronald. 1996. “Leonhard Euler: The First St. Petersburg Years (1727–1741),” Historia Mathematica 23: 121–166.
5. Dickson, L. E. 1952. History of the Theory of Numbers, Vol. 1: Divisibility and Primality, New York: Chelsea.