1. Work performed at Westinghouse Laboratories byF. F. Lange andR. Kossowsky, published in ARPA report, ?Brittle Materials Design, High Temperature Gas Turbine,? AMMRC CTR73-9 (March 1973).
2. H. R. Baumgartner andD. W. Richerson, in ?Fracture Mechanics of Ceramics? (Plenum Press, New York, 1974) Vol 1, p, 367.
3. A. G. Evans andS. M. Wiederhorn, NBSIR 73-147 (March 1973);
4. A. G. Evans andS. M. Wiederhorn, NBSIR 73-147 (March 1973);
5. A. G. Evans andS. M. Wiederhorn, NBSIR 73-147 (March 1973);Intl. J. Frac., in press.