@inbook{ComplexityConstraintLanguages,
  title = "The complexity of constraint languages",
  author = "David Cohen and Peter Jeavons",
  year = "2006",
  booktitle = "Handbook of Constraint Programming",
  chapter = "8",
  publisher = "Elsevier",
  url = "http://www.comlab.ox.ac.uk/activities/constraints/publications/ComplexityLanguages.pdf",
}