@Article{ 
  belhopnov09,
  author = { Bellettini, Giovanni and Hoppe, Jens and Novaga, Matteo and Orlandi, Giandomenico },
  title = { Closure and convexity properties of closed relativistic strings },
  journal = { Complex Analysis and Operator Theory },
  year = { 2010 },
  volume = { 4 },
  number = { 3 },
  pages = { 473-496 },
  URL = { http://cvgmt.sns.it/paper/1049/ },
  note = { cvgmt preprint}
}