1. MONTEDISON S. P. A.: Japan Pat. (Open), 48?16986 (1973)
2. MITSUI PETROCHEMICAL INDUSTRIES: Japan Pat. (Open), 50?126590 (1975)
3. PINO, P., R. MULHAPT: Angew. Chem. Int. Ed. Engl.19, 857 (1980)
4. KASHIWA, N.: ?MMI International Symposium on Transition Metal Catalyzed Polymerization (Midland)?, p. 13 (1981)
5. KEII, T.: ibid. p. 6 (1981)