1. R. H. J. Hannink andM. V. Swain,J. Aust. Ceram. Soc. 18 (1963) 53.
2. L. Li andR. F. Pabst, ?Fracture and Fatique?, Proceedings of 3rd European Colloquium on Fracture, edited by J. C. Radon (Pergamon, New York, 1980 pp. 251?55.
3. L. K. Lenz andA. H. Heuer,J. Amer. Ceram. Soc. 65 (1982) 190?191.
4. P. F. Becher,Amer. Ceram. Soc. Bull. 61 (1982) 338.
5. S. W. Freiman, D. R. Mulville andP. W. Mast,J. Mater. Sci. 8 (1973) 1527.