1. SAE Handbook 1972, pp. 15–18.
2. B. A. James and G. T. Brown:Metal Forming, May 1968, pp. 124–31.
3. M. A. Grossmann:Tram. AIME, 1942, vol. 150, p. 227.
4. W. Crafts and J. L. Lamont: “Hardenability and Steel Selection”, Pitman, 1949.
5. G. R. Brophy and A. J. Miller:Trans. AIME, 1946, vol. 167, p. 654.