1. P. Pascal, Nouveau traité de Chimie Minérale, Vol. IV, Masson & Cie Editeurs, Massort & Cie, Paris, 1958, pp. 612, 613.
2. C. Duval, Traité de microanalyse minérale qualitative et quantitative, Vol. I, Presses Scientifiques Internationales, Paris, 1954, p. 368.
3. J. Smith, Acta Cryst., 6 (1953) 604, referred to in the paper 1.
4. L. I. Mirkin, Collection of Data on X-Ray Analysis of the Structure of Polycrystals, Gosudarstvenoe Izdatelstvo Fizico-Matematicescoi Literaturi, Moscow, 1961, p. 581.
5. W. M.Latimer, Oxid. Pot. IIed, 1952, referred to in the paper 9.