@Article{ 
  balric,
  author = { Balogh, Zoltan and Rickly, Matthieu },
  title = { Regularity of convex functions on Heisenberg groups },
  journal = { Ann. Scuola Norm. Sup. Pisa },
  year = { 2003 },
  volume = { II },
  number = { 5 },
  pages = { 847-868 },
  URL = { http://cvgmt.sns.it/paper/1528/ },
  note = { cvgmt preprint}
}