1. P. C. Paris, G. C. Sih, ASTM Special Tech. Publ. No. 381 (1965).
2. W. F. Brown, J. E. Srawley, ASTM Special Tech. Publ. No. 410 (1966).
3. A. G. Evans, G. Tappin, Proc. Brit. Ceram. Soc. 20, 275 (1972).
4. See for example A. S. Tetelman and A. J. McEvily, Fracture of Structural Materials ( Wiley, New York ) 1967.
5. S. M. Wiederhorn, this volume.