1. and in : Proc. 5th Internat. Congr. on Catalysis, 1972. Miami Beach. Florida. North-Holland Publ. Co., Amsterdam 1973, Abstract 29-465;
2. Belg. Pat. 721686 (1969).
3. and in : Proc. 5th Internat. Congr. on Catalysis, 1972, Miami Beach, Florida. North-Holland Publ. Co., Amsterdam 1973, Abstract 30-477;