@Article{ 
  san05,
  author = { Santambrogio, Filippo },
  title = { Transport and Concentration Problems with Interaction Effects },
  journal = { J. Glob. Opt. },
  year = { 2007 },
  volume = { 38 },
  number = { 1 },
  pages = { 129-141 },
  URL = { http://cvgmt.sns.it/paper/934/ },
  note = { cvgmt preprint}
}