@Misc{ 
  monmor04a,
  author = { Monti, Roberto and Morbidelli, Daniele },
  title = { Kelvin transform for Grushin operators and critical semilinear equations },
  journal = { Duke Math. J. },
  year = { 2005 },
  pages = {  },
  URL = { http://cvgmt.sns.it/paper/581/ },
  note = { cvgmt preprint}
}