@INBOOK{CABook-EmpiricalHardness,
  AUTHOR =       {Kevin Leyton-Brown and Eugene Nudelman and Yoav Shoham},
  editor =       {Peter Cramton and Yoav Shoham and Richard Steinberg},
  TITLE =        {Empirical Hardness Models for Combinatorial Auctions},
  CHAPTER =      {19},
  PUBLISHER =    {MIT Press},
  PAGES =        {479--504},
  YEAR =         {2006}
}