1. D. L. Kepert, Comprehensive Inorganic Chemistry, Vol. 4, A. F. Trotman Dicksenson et al. Eds., Pergamon Press, Oxford, 1973, chapter 51.
2. C. F. Baes, Jr. and R. E. Mesmer, The Hydrolysis of Cations, Wiley, New York, 1976.
3. K. H. Tytko and O. Glemser, Adv. Inorg. Chem, 19 (1976) 239.
4. M. T. Pope, Heteropoly and Isopoly Oxometalates, Springer Verlag, Berlin, Heidelberg, New York, Tokyo, 1983.
5. P. Souchay, M. Boyer and F. Chauveau, Kgl. Tek. Hoegsk. Handl. No 259 (1972)