@Article{ 
  LeLeMoVi12,
  author = { Le Donne, Enrico and Leonardi, Gian Paolo and Monti, Roberto and Vittone, Davide },
  title = { Extremal curves in nilpotent Lie groups },
  journal = { GAFA Geometric and Functional Analysis },
  year = { 2013 },
  volume = { 23 },
  number = { 4 },
  pages = { 1371--1401 },
  URL = { http://cvgmt.sns.it/paper/1882/ },
  note = { cvgmt preprint}
}