@Article{ 
  baltys,
  author = { Balogh, Zoltan and Tyson, Jeremy },
  title = { Potential theory in Carnot groups },
  journal = { AMS Series in Contemporary Mathematics },
  year = { 2003 },
  volume = { 320 },
  pages = { 15-27 },
  URL = { http://cvgmt.sns.it/paper/211/ },
  note = { cvgmt preprint}
}