@Article{ 
  Mag6a,
  author = { Magnani, Valentino },
  title = { Spherical Hausdorff measure of submanifolds in Heisenberg groups  },
  journal = { Ricerche Mat. },
  year = { 2006 },
  volume = { 54 },
  number = { 2 },
  pages = { 607-613  },
  URL = { http://cvgmt.sns.it/paper/1731/ },
  note = { cvgmt preprint}
}