1. R.O. Ritchie et al., Journal of the Mechanics and Physics of Solids 21 (1973) 395?410.
2. J.F. Knott, Fundamentals of Fracture Mechanics, Butterworths, London (1973).
3. [3] K. Wobst and D. Aurick, in ICF 4, 2 (1977) 183.
4. [4] H. Krafa et al., in ICF 5 (1980) 881?888.
5. M. Yao et al., ICF 6, 2 (1984) 1423?1430.