1. L. GUILLET, in ?Report of Conference on Strength of Solids?, (The Physical Society, London, 1948) p. 116.
2. P. FELTHAM,J. Inst. Metals 89 (1960?1961) 210.
3. P. FELTHAM and G. J. COPLEY,Acta Metall. 8 (1960) 542.
4. Idem, Phil. Mag. 5 (1960) 649.
5. M. Z. BUTT and I. M. GHAURI,Phys. Status Solidi (a), Submitted.