1. I. R. Kramer and J. Deimer:Prog. Met. Phys., 1968, vol. 9, p. 131.
2. E. S. Machlin:Strengthening Mechanism in Solids, p. 375, ASM, Novelty, Ohio, 1962.
3. A. R. C. Westwood:Environment-Sensitive Mechanical Behavior, p. 1, Gordon and Breach, New York, 1966.
4. J. C. Fischer:Trans. AIME, 1952, vol. 194, p. 531.
5. A. K. Head:Phil. Mag, 1953, vol. 44, p. 92.