1. T. Angel,J. Iron Steel Inst. 177 (1954) 165.
2. B. Cina,ibid 177 (1954) 406.
3. K. M. Carlsen andK. C. Thomas,ASM Trans. Quart. 55 (1962) 462.
4. S. Floreen andG. W. Tuffnell,ibid 57 (1964) 301.
5. E. B. Kula, Proceedings of the Twelfth Sagemore Army Materials Research Conference on Strengthening Mechanisms, edited by J. J. Burke, N. L. Reed and V. Weiss (Syracuse University Press, 1966) pp. 83?122.