Q:\CHOICE\RUBIN.TXT 2001 May 9 references: Herman Rubin and Jean E. Rubin, "Equivalents of the Axiom of Choice," North-Holland Publishing Company, Amsterdam, 1963. Jean E. Rubin, "Set Theory for the Mathematician," Holden-Day Inc., San Francisco, 1967. According to Rubin and Rubin (1963), the following formulation of the axiom of choice was stated in 1906 by Bertrand Russell, and in 1908 by Zermelo: If t is a disjoint collection of nonempty sets, there exists a set C which consists of one and only one element from each set in t. The references given are: Bertrand Russell, 1906, "On some difficulties in the theory of transfinite numbers and order types," Proc. London Math. Soc. (2) vol. 4, pp. 29-53. E. Zermelo, 1908, "New proof for the wellordering," Math. Annalen vol. 65, pp. 107-128. [in German] There is also an earlier 1904 paper by Zermelo on the well ordering theorem: E. Zermelo, 1904, "Proof that every set can be wellordered," Math. Annalen vol. 59, pp. 514-516. English translations for both of Zermelo's papers are given in van Heijenoort's source book (1967). Jean van Heijenoort, 1967, "From Frege to G\"odel. A Source Book in Mathematical Logic, 1879-1931," Harvard University Press, Cambridge, Massachusetts.