[1] CERN,GENEVA,SWITZERLAND
[2] UNIV DORTMUND,INST PHYS,D-4600 DORTMUND 50,FED REP GER
[3] UNIV HEIDELBERG,INST HOCHENERGIEPHYS,D-6900 HEIDELBERG 1,FED REP GER
[4] CENS,DEPT PHYS PARTICULES ELEMENTAIRES,F-91190 GIF SUR YVETTE,FRANCE
[5] UNIV BOLOGNA,IST FIS,I-40126 BOLOGNA,ITALY