Apt99'

@article{DBLP:journals/tcs/Apt99,
  author    = {Krzysztof R. Apt},
  title     = {The Essence of Constraint Propagation},
  journal   = {Theor. Comput. Sci.},
  volume    = {221},
  number    = {1-2},
  year      = {1999},
  pages     = {179-210},
  ee        = {http://dx.doi.org/10.1016/S0304-3975(99)00032-8},
  bibsource = {DBLP, http://dblp.uni-trier.de}
}