@Misc{ 
  juulugman05,
  author = { Juutinen, Petri and Lu, Guozhen and Manfredi, Juan and Stroffolini, Bianca },
  title = { "Convex functions on Carnot groups " },
  journal = { Revista Matematica Iberoamericana },
  year = { 2005 },
  pages = {  },
  URL = { http://cvgmt.sns.it/paper/159/ },
  note = { cvgmt preprint}
}