1. M. Takatsu, J. Takahashi, T. Nishikawa, K. Ohya and A. Hattori, J.Ceram.Soc.Jpn., 98,1343–48(1990)
2. T. Yamamoto, H. Igarashi and K. Okazaki, Ferroelectrics,50, 273–78 (1983)
3. K. Mehta and A.V. Virkar, J. Am. Ceram. Soc., 73, 567–74(1990)
4. J.G. Bruce, W.W. Gerberich and B.G. Koepke, in “Fracture Mechanics of Ceramics, vol.4, Ed. by R.C. Bradt, U.P.H. Hasselman and F.F. Lange, p.687–709, Plenum Press, New York, (1978)
5. S.W. Freiman, K.R. McKinney and H.L. Smith, “Fracture Mechanics of Ceramics, vol.4, Ed. by R.C. Bradt, D.P.H. Hasselman and F.F. Lange, p.659–76, Plenum Press, New York, (1978)