1. B. H. C. Waters:Metal Treatment and Drop Forging, 1953, vol. 19, pp. 79–83.
2. B. H. C. Waters:Metal Treatment and Drop Forging, 1953, vol. 19, pp. 103–09.
3. G. Siebel, D. Altenpohl, and M. Cohen:Z.f. Metallkunde, 1953, vol. 44, pp. 1973–83.
4. D. R. Thornton:Journal of the Iron and Steel Institute, 1956, vol. 183, pp. 300–15.
5. D. L. Collins:Metallurgia, 1976, vol. 76, pp. 137–44.