1. R. W. Heckel: Trans ASM, 1964, Vol. 57, No. 2, page 443.
2. J. E. White: Trans ASM, 1964, Vol. 57, No. 3, page 756.
3. R. C. Westgren, V. R. Thompson, and V. C. Peterson: WADD TR 61-134, Part II, Crucible Steel Co. of America, Pittsburg, (April 1963).
4. L. J. Stephen, F. N. Lake, and C. R. Cook: ML TDR 64-271, Thompson Ramo Wooldridge, Cleveland (September 1964).
5. R. Murphy and N. J. Grant: Powder Met., Autumn 1962, page 10.