@Article{ 
  magvit06,
  author = { Magnani, Valentino and Vittone, Davide },
  title = { An intrinsic measure for submanifolds in stratified groups },
  journal = { J. Reine Angew. Math. },
  year = { 2008 },
  volume = { 619 },
  pages = { 203-232 },
  URL = { http://cvgmt.sns.it/paper/205/ },
  note = { cvgmt preprint}
}