@Article{ 
  FocSpa11,
  author = { Focardi, Matteo and Spadaro, Emanuele },
  title = { An intrinsic approach to manifold constrained variational problems },
  journal = { Annali di Matematica Pura e Applicata },
  year = { 2013 },
  doi = { 10.1007/s10231-011-0216-z },
  volume = { 192 },
  pages = { 145-163 },
  URL = { http://cvgmt.sns.it/paper/1716/ },
  note = { cvgmt preprint}
}