1. A. Montes, R. Roque-Malherbe and E. D. Shchukin, 31 (1986) 37.
2. A. Picart, PhD Dissertation. National Center for Scientific Research Havana, Cuba, December 1984.
3. L. Lopez-Colado and R. Roque-Malherbe, In preparation.
4. D. W. Breck, Zeolite Molecular Sieves. John Wiley and Sons, New York, 1974, Chapter 5.