1. E. M. Flanigen , B. M.Lok, R. L.Patton and S. T.Wilson, in New Developments in Zeolite Science and Technology, ed. Y. Murakami, A. Iijima and J. W. Ward, Kodansha, Tokyo, 1986, p. 103.
2. R. A. Schoonheydt , R.de Vos and J.Pelgrims and H.Leeman, in Zeolites, Facts, Figures, Future, ed. P. A. Jacobs and R. A. van Santen, Elsevier, Amsterdam, 1989, p. 559.
3. F. A. Cotton and G.Wilkinson, Advanced Inorganic Chemistry, John Wiley, New York, 1982, p. 725.
4. E. M. Flanigen , R. L.Patton and S. T.Wilson, in Innovation in Zeolite Materials Science, ed. P. J. Grobet, W. J. Mortier, E. F. Vansant and G. Schulz-Ekloff, Elsevier, Amsterdam, 1988, p. 13.