@article{Asinetal2011Constraints,
  author    = {Roberto As\'{\i}n and
               Robert Nieuwenhuis and
               Albert Oliveras and
               Enric Rodr\'{\i}guez-Carbonell},
  title     = {{Cardinality Constraints: a Theoretical and Empirical Study}},
  journal   = {Constraints},
  note      = {To appear.}
}