1. H. E. McGannon, (Ed.), ?The Making Shaping and Treating of Steel?, 9th edn. (United States Steel Co., Pittsburg, Pennsylvania, 1971) p. 1203.
2. J. G. Williams andJ. E. Croll,J. Aust. Inst. Met. 21 (1976) 88.
3. A. H. Cottrell, ?Conference on the Strength of Solids? (Physical Society, London, 1948) p. 30.
4. N. F. Mott andF. R. N. Nabarro,ibid?, p. 1.
5. E. Orowan, ?Symposium Internal Stresses in Metals and Alloys? (Institute of Metals, London 1947) p. 47.