References
- Amin , M. Bull. of the 2nd Conf. of Solids. Cairo Univ. Cairo Univ. .
- Fernelius , W. C. 1946 . Ind. Synthesis , Vol. 2 , N.Y. : McGraw-Hill .
- Harman , G. G. 1957 . Let. to Editor, Phys. Rev. , 135 : 8
- Kamel , R. and Hilal , M. 1975 . Mol. Cryst. Liq. Cryst. , 31 : 9
- Mountvala , A. J. 1971 . J. Amer. Ceram. Soc. , 54 : 544
- Orsa, A. (1959)
- Raymonode , B. R. 1956 . Acta Cryst. , 9 : 781
- Tawfik , A. and Molokhia , N. 1979 . Acta Phys. Polonica , : 155