1. F.J. Berry: Adv. Catalysis 30, 97 (1982)
2. J.C. Giuntini, W. Granier, J.V. Zanchetta, A. Taha: J. Mater. Sci. Lett. 9, 138 (1990)
3. K. Sato, A. Yamamato, M. Nomura: Japan Patent Application 90, 35, 915 (1990)
4. M.O. Osmanov: Azerb. Khim. Zh. 24, 1 (1986)
5. L. Hegedus, J.W. Beckman, W.H. Pan, J.P. Solor: European Patent Application 345, 695 (1989)