Neutrino mass spectrum and lepton mixing
  The program of reconstruction of the neutrino mass and flavor spectrum is outlined and the present status of research is summarized. We describe the role of future solar and atmospheric neutrino experiments, detection of the Galactic supernovae and double beta decay searches in accomplishing this program. The LSND result and four neutrino mass spectra are considered in connection with recent searches for the sterile components in the solar and atmospheric neutrino fluxes. 
A. Yu. Smirnov