1. Marlex Catalyst Systems
2. a Belg. Pat. 530 617 (1955) to Phillips Petroleum Co., USA
3. b U.S. Pat. 2 825 721 (1958) to Phillips Petroleum Co., USA
4. c Brit. Pats. 790 195 and 790 196 (1958) to Phillips Petroleum Co., USA.
5. U.S. Pat. 3 878 179 (1969) to Phillips Petroleum Co., USA.