1. E. I. Salkovitz: AIME Trans., 1956, vol. 206, p. 176; JOURNAL OF METALS, February 1956.
2. P. Niggli: Handbuch der Experimental Physik, 1928, vol. 7, part 1, p. 151.
3. C. S. Barrett: Structure of Metals, pp. 189, 632. 2nd Ed. McGraw-Hill Pub. Co. Ltd. London, 1953.