1. A. G. Lamas, Margarida Almeida andH. M. M. Diz,Ceram. Int., accepted.
2. R. Moreno, J. S. Moya andJ. Requena,Bol. Soc. Esp. Ceram. Vidr. 26 (1987) 355.
3. K. Chou andL. Lee,J. Amer. Ceram. Soc. 72 (1989) 1622.
4. G. L. Messing, K. S. Mazdiyasni, J. W. McCauley andR. A. Haber (eds), ?Advances in Ceramics?, Vol. 21, ?Ceramic Powder Science? (American Ceramic Society, Westerville, OH, 1987) pp. 495?516.
5. B. C. Bonekamp, M. J. Schoute andM. J. A. A. Goris, in ?Euro-Ceramics?, Vol. 1, edited by G. With, R. A. Terpstra and R. Metselaar (Elsevier Applied Science, London, New York, 1989) pp. 223?7.