1. The role of hafnium in supported titanium/hafnium catalysts for olefin polymerization
2. F. Ciardelli, F. Masi, S. Malquori, C. Ferrero, L. Barazzoni, F. Menconi, A. Moalli and R. Invernizzi (Enichem Anic), Ital. Pat. 22115A (1988).
3. F. Masi, A. Moalli, R. Invernizzi, F. Menconi, C. Ferrero, S. Malquori, L. Barazzoni and P. Polesello (Enichem Anic), Ital. Pat. 21877A (1988).
4. N. Zandona' and F. Ciardelli, Atti IX Convegno AIM, Bologna, 16–20 Oct., 1989.