1. I. Udrea, E. Groner, L. Frunza: React. Kinet. Catal. Lett.,53, 451 (1994).
2. For a review, see H. Knözinger: in Acid-Base Catalysis (K. Tanabe et al. Eds.), Kodansha, 1989, and reference herein.
3. H.G. Karge: in Catalysis and Adsorption by Zeolites (G. Öhlman et al. Eds), Elsevier 1991.
4. L. Frunza, M. Udrea, I. Udrea, C. Capat, D. Crisan, I.V. Nicolescu: Rev. Roum. Chim.,35, 221 (1990).
5. F. Solymosi, A. Erdőhely, T. Bánsági: J. Chem. Soc. Faraday I,77, 2645 (1981).