1. G. Vagnard and J. Washburn, J. Amer. Ceram, Soc. 51 (1968) 88.
2. A.F. Wells, ?Structural Inorganic Chemistry? (Oxford, 1962).
3. H.W. Swanson and R.K. Fugat, ?Standard X-Ray Diffraction Powder Patterns?, Vol. II (National Bureau of Standards, USA), Cire No. 539 23 (1953).
4. R.E. Tylecote, J. Inst. Metals 78 (1950) 301
5. R.S. Toth, R. Kilkson and D. Trivich, J. Appl. Phys. 31 (1960) 1117.