1. W. Weibull, J. Appl. Mech. 18 (1951) 293.
2. G. C. Sih, Int. J. Fracture 10 (1974) 305.
3. A. De S. Jayatilaka, I. J. Jenkins and S. V. Prasad, 4th International Conference on Fracture, Canada (June 1976). (ICF4 Publ., Waterloo, 1976).
4. J. D. Poloniecki, D. Phil. Thesis, University of Sussex. 1974
5. J. D. Poloniecki and T. R. Wilshaw, Nature 229 (1971) 226.