A Study of Bs0 Meson Oscillation Using Hadronic Z0 Decays Containing Leptons   
  
A sample of Z0 decays containing b-flavoured hadrons is tagged using leptons,  
and events having precise proper time measurements are selected. These         
events are used to study Bs0 oscillations. The flavour (b or bbar) at          
decay is determined from the lepton charge while the flavour at production     
is determined from jet charge or the charge of a second lepton, where          
available. The experiment was not able to resolve the oscillatory              
behaviour, and we deduce that the Bs0 oscillation frequency                    
delta m_s > 5.2 ps^-1 at the 95% confidence level.                             
  
 Parallel session :7                   
 Plenary  session :3