WO9920590-A1 -- DE19622331-A1   BASF AG (BADI)   TENTEN A,  PROLL T,  SCHILDBERG H;  EP575897-A1   BASF AG (BADI)   NEUMANN H,  MARTAN H,  PETERSEN H,  DOERFLINGER W;  FR2756499-A1   ELF ATOCHEM SA (AQOR)   SIMON M,  DAUBREGE F,  ETIENNE E,  PHAM C;  GB1340891-A   POWER - GAS CORP LTD (POGC);  IMPERIAL CHEM IND LTD (ICIL);  GB1398385-A   ;  JP02083348-A   ;  US2625519-A   ;  US5191116-A   ASAHI KASEI KOGYO KK (ASAH)   YAMAMATSU S,  YAMAGUCHI T;  US5198580-A   STANDARD OIL CO OHIO (STAH)   BARTEK J P,  EBNER A M,  BRAZDIL J F;  EP1025073-B1 -- DE19622331-A1   BASF AG (BADI)   TENTEN A,  PROLL T,  SCHILDBERG H;  EP575897-A1   BASF AG (BADI)   NEUMANN H,  MARTAN H,  PETERSEN H,  DOERFLINGER W;  FR2756499-A1   ELF ATOCHEM SA (AQOR)   SIMON M,  DAUBREGE F,  ETIENNE E,  PHAM C;  GB1340891-A   POWER - GAS CORP LTD (POGC);  IMPERIAL CHEM IND LTD (ICIL);  GB1398385-A   ;  JP02083348-A   ;  US2625519-A   ;  US5191116-A   ASAHI KASEI KOGYO KK (ASAH)   YAMAMATSU S,  YAMAGUCHI T;  US5198580-A   STANDARD OIL CO OHIO (STAH)   BARTEK J P,  EBNER A M,  BRAZDIL J F;  US6541664-B1 -- CA971568-A   SQUIBB & SONS INC E R (SQUI);  DURSCH F (DURS-Individual);  CN1105352-A   DAQING PETROLEUM COLLEGE (DAQI-Non-standard)   WANG Z,  LIU G,  ZHAO R;  DE19530454-A1   ;  DE19622331-A1   BASF AG (BADI)   TENTEN A,  PROLL T,  SCHILDBERG H;  EP117146-A   HALCON SD GROUP INC (HALC)   KHOOBIAR S,  PORCELLI R;  EP575897-A1   BASF AG (BADI)   NEUMANN H,  MARTAN H,  PETERSEN H,  DOERFLINGER W;  EP608838-A2   MITSUBISHI KASEI CORP (MITU);  MITSUBISHI CHEM CORP (MITU)   USHIKUBO T,  NAKAMURA H,  KOYASU Y,  WAJIKI S;  FR2693384-A1   ;  FR2756499-A1   ELF ATOCHEM SA (AQOR)   SIMON M,  DAUBREGE F,  ETIENNE E,  PHAM C;  GB1340891-A   POWER - GAS CORP LTD (POGC);  IMPERIAL CHEM IND LTD (ICIL);  GB1398385-A   ;  JP02083348-A   ;  US2625519-A   ;  US4066704-A   POWER - GAS CORP LTD (POGC);  IMPERIAL CHEM IND LTD (ICIL);  US5191116-A   ASAHI KASEI KOGYO KK (ASAH)   YAMAMATSU S,  YAMAGUCHI T;  US5198580-A   STANDARD OIL CO OHIO (STAH)   BARTEK J P,  EBNER A M,  BRAZDIL J F;  US5364825-A   BASF AG (BADI)   NEUMANN H,  MARTAN H,  PETERSEN H,  DOERFLINGER W;  WO1997036849-A1