1. J. W.Mellor, A Comprehensive Treatise on Inorganic and Theoretical Chemistry, 3rd ed., Vol. 3 Longmans, 1937.
2. T. R. Ingraham andM. Rigaud, Canadian Met. Quarterly, 4, 237 and 257 (1965).
3. P. Groth, Chemische Kristallographie, Engelmann, Leipzig, 1906.
4. E. M.Chamot and C. W.Mason, Handbook of Chemical Microscopy, 3rd ed., Wiley, 1958.
5. J. M. Thomas andT. A. Clarke, J. Chem. Soc. A, 457 (1968).