@Article{ 
  AgrBarRiz15,
  author = { Agrachev, Andrei and Barilari, Davide and Rizzi, Luca },
  title = { Sub-Riemannian curvature in contact geometry },
  journal = { Journal of Geometric Analysis },
  year = { 2015 },
  doi = { 10.1007/s12220-016-9684-0 },
  pages = {  },
  URL = { http://cvgmt.sns.it/paper/2699/ },
  note = { cvgmt preprint}
}