@INPROCEEDINGS{PenVen05,
  AUTHOR =       {P. Penna and C. Ventre},
  TITLE =        {Free-riders in {Steiner} tree cost-sharing games},
  BOOKTITLE =    {Proc. of the 12th Colloquium on Structural Information and Communication Complexity (SIROCCO)},
  YEAR =         {2005},
  volume =       {3499},
  series =       {LNCS},
  pages =        {231-245}
}