1. Nomura, S., et al. (Sekesui Chemical Co.), United States patent, 4,452,935 (1984).
2. Hermann, H. D., et al. (Hoechst Aktiengesellschaft), United States patent, 4,205,146 (1980).
3. Tadoki, I., et al. (Sekesui Chemical Co.), Japan patent, 30706 (1982).
4. Dauvergne, P. (Saint-Gobain Industries), United Kingdom patent, 2,007,677 (1982).
5. Cartier, G. E. & Farmer, P. H. (Monsanto Co.), United States patent, 4,874,814 (1989).