[en] Using the ARGUS detector at the e⁺e^- storage ring DORIS II at DESY an update of the B⁰-anti B⁰ mixing measurement has been performed including the new 1988 data. With a total of ∫ Ldt = 172 pb^-1 on the Υ(4S) resonance and 55 pb^-1 in the nearby continuum the dilepton analysis yields a mixing parameter of r = 0.22 ± 0.07 ± 0.06. The authors have also investigated charge correlations between a D*⁺ and one or two leptons. Combining the results of all three methods they obtain r = 0.22 ± 0.07. 7 refs., 2 figs., 3 tabs