@Article{ 
  AgrBar12,
  author = { Agrachev, Andrei and Barilari, Davide },
  title = { Sub-Riemannian structures on 3D Lie groups },
  journal = { J. Dynam. Control Systems },
  year = { 2012 },
  volume = { 18 },
  number = { 1 },
  pages = { 21-44 },
  URL = { http://cvgmt.sns.it/paper/1795/ },
  note = { cvgmt preprint}
}