1. Langmuir, I., J. Frank. Inst., 217, 543 (1934).
2. Van Liempt, J. A. M., Rec. trav. chim., 51, 114 (1932).
3. Zwikker, C., Physica, 7, 189 (1927).
4. Mehl, R. F., Trans. Amer. Inst. Mining and Metallurgical Eng., 122, 11 (1936).
5. Seith, W., and Keil, C. A., Z. Metallkunde, 25, 104 (1933).