1. M. W. Birch, J. G. Williams andG. P. Marshall, Third International Conference on Deformation, Yield and Fracture of Polymers, Cambridge, (The Plastics and Rubber Institute, London, 1976) pp. 6.1?6.7.
2. Y. W. Mai andJ. G. Williams,J. Mater. Sci. 12 (1977) 1376.
3. I. G. Zewi, W. J. Rudik andR. D. Corneliussen,Polymer Eng. Sci. 20 (1980) 622.
4. G. P. Marshall, N. H. Linkins, L. E. Culver andJ. G. Williams,SPE J 28 (1972) 26.
5. P. L. Fernando andJ. G. Williams,Polymer Eng. Sci. 20 (1980) 215.