1. C. C. Hsaio and J. A. Sauer, J. Appl. Phys. 21 (1950) 1071.
2. O. K. Spurr, Jr and W. D. Nieglish, J. Appl. Polymer Sci. 6 (1962) 585.
3. R. P. Kambour, J. Polymer Sci. D7 (1973) 1.
4. S. Rabinowitz and P. Beardmore, CRC Crit. Rev. Macromol. Sci. 1 (1972) 1.
5. E. J. Kramer, in ?Developments in Polymer Fracture?, edited by E. H. Andrews (Applied Science Publishers, Barking, Essex, 1979) p. 51.