1. Eppelsheimer, D. S., and Reitsma, jun., L. J., Nature, 182, 339 (1958).
2. Jaffee, R. I., and Weiss, S. M., Materials and Methods, 36 (3), 113 (1952).
3. Quoted in Nat. Bur. Stand. Circ. C, 447, “Mechanical Properties of Metals and Alloys”, p. 416 (1943).