@Article{ 
  ambdelman99,
  author = { Ambrosio, Luigi and De Lellis, Camillo and Mantegazza, Carlo },
  title = { Line Energies for Gradient Vector Fields in the Plane },
  journal = { Calc. Var. },
  year = { 1999 },
  volume = { 9 },
  pages = { 327-355 },
  URL = { http://cvgmt.sns.it/paper/1570/ },
  note = { cvgmt preprint}
}