1. (a) M.T. Pope, A. Muller (Eds.), Polyoxometalate Chemistry Kluwer, Dordercht, The Netherlands, 2001;
2. (b) Polyoxometalates, Chem. Rev. 98 (1998) 1.
3. (a) M.T. Pope, Heteropoly and Isopoly Oxometalates, Springer-Verlag, New York, 1983;
4. (b) M.T. Pope, A. Müller, Angew. Chem. Int. Ed. Engl. 30 (1991) 34;
5. (c) S.M. Kuznicki, K.A. Thrush, F.M. Allen, S.M. Levine, M.M. Hamil, D.T. Hayhurst, M. Mansour, in: M.L. Occelli, H.E. Robson (Eds.), Synthesis of Microporous Materials, vol. 1, Van Nostrad Reinhold, New York, 1992, p. 427;