1. M. L. Kronberg and F. H. Wilson, Trans. TMS-AIME, 185, 501 (1949).
2. P. A. Beck and H. Hu, Trans. TMS-AIME, 182, 627 (1949).
3. F. C. Frank, referred by ref. 5.
4. K. T. Aust and, J. W. Rutter, Trans. TMS-AIME, 215, 119 (1959).
5. K. T. Aust and J. W. Rutter, Trans. TMS-AIME, 215, 820 (1959).