@Article{ 
  cramal07,
  author = { Crasta, Graziano and Malusa, Annalisa },
  title = { The distance function from the boundary in a Minkowski space. },
  journal = { Trans. Amer. Math. Soc. },
  year = { 2007 },
  volume = { 359 },
  pages = { 5725-5759 },
  URL = { http://cvgmt.sns.it/paper/394/ },
  note = { cvgmt preprint}
}