@Article{ 
  fraserser02a,
  author = { Franchi, Bruno and Serapioni, Raul and Serra Cassano, Francesco },
  title = { On the structure of finite perimeter sets in step 2 Carnot groups },
  journal = { J.Geom.Anal. },
  year = { 2003 },
  volume = { 13 },
  number = { 3 },
  pages = { 421-466 },
  URL = { http://cvgmt.sns.it/paper/952/ },
  note = { cvgmt preprint}
}