@Article{ 
  Pao12,
  author = { Paolini, Emanuele },
  title = { Minimal connections: the classical Steiner problem and generalizations },
  journal = { Bruno Pini Mathematical Analysis Seminar },
  year = { 2012 },
  volume = { 3 },
  number = { 1 },
  pages = { 72 },
  URL = { http://cvgmt.sns.it/paper/2240/ },
  note = { cvgmt preprint}
}