@Misc{ 
  monmat04,
  author = { Monti, Roberto and Rickly, Matthieu },
  title = { Geodetically convex sets in the Heisenberg group },
  journal = { J. Convex Anal. },
  year = { 2004 },
  pages = {  },
  URL = { http://cvgmt.sns.it/paper/83/ },
  note = { cvgmt preprint}
}