1. F. Th�mmler andG. Grathwohl, in ?MRS International Meeting on Advanced Materials?, Vol. 4 edited by M. Doyana, S. Somiya and R. P. H. Chang (Materials Research Society, Pittsburgh, PA, 1989) pp. 237?53.
2. O. Van Der Biest, S. Valkiers, L. Garguet, P. Tambuyser andI. Baele,Br. Ceram. Proc. 39 (1987) 33.
3. M. G�rtler andG. Grathwohl, in ?Proceedings of the 4th International Conference on Creep and Fracture of Engineering Materials and Structures? (Institute of Metals, London, 1989) pp. 399?408.
4. N. J. Tighe, S. M. Wiederhorn, T.-J. Chuang andC. L. McDaniel, in ?Deformation of Ceramic Materials II?, edited by R. E. Tressler and R. C. Bradt (Plenum Press, New York, 1984) pp. 587?603.
5. D. S. Wilkinson andM. M. Chadwick, in ?Proceedings of the 11th Ris� International Symposium on Metallurgy and Materials Science?, edited by J. J. Bentzen J. B. Bilde-Sorensen, N. Christiansen, A. Horsewell and B. Ralph (Ris� National Laboratory, Roskilde, 1990) pp. 517?22.