1. 1) Wentrup, H and B. Knapp: Tech. Mit. Krupp., 4 (1941), 237 J. Iron Steel Inst., 180 (1955), 116
2. 2) Chen, H.M and J. Chipman: Trans. Am. Soc. Metals, 38 (1947), 70
3. 4) Turkdogan, E.T: J. Iron Steel Inst., 178 (1954), 218
4. 5) Hilty, D.C, W.D. Forgeng and R.L. Folkman: Trans. Am. Inst. Min. Met. Engrs., 203 (1955), 253
5. 6) Hilty, D.C.: ibid, 185 (1949), 91