Neutrinoless Double $\beta$-Decay: Status and Future
  A brief summary of the status of neutrino masses, mixing and oscillations is presented. Neutrinoless double $\beta$-decay is considered. Predictions for the effective Majorana mass are reviewed. A possible test of the calculations of nuclear matrix elements of the $0\nu\beta\beta$-decay is proposed. 
S. M. Bilenky