@article{Lavoura:2001nt,
  author = "Lavoura, Luis",
  title = "{Softly broken lepton numbers: an approach to maximal neutrino mixing  }",
  doi = "10.22323/1.007.0197",
  journal = "PoS",
  year = 2001,
  volume = "hep2001",
  pages = "197"
}