References
L. L. FEHRENBACHER and L. A. JACOBSON,J. Amer. Ceram. Soc. 48 (1965) 9.
E. RYSHKEWITCH, in “Oxide ceramics — physical chemistry and technology” (Academic Press) p. 375.
D. J. GREEN, D. R. MAKI and P. S. NICHOLSON,J. Amer. Ceram, Soc. 57 (1974) 136.
R. M. SLEPIAN, ibid.47 (1964) 535.