@Article{JCSCexpand,
  author = 	 {Geeraerts, G. and Raskin, J.-F. and {Van~Begin}, L.},
  title = 	 {{E}xpand, {E}nlarge and {C}heck: new algorithms for the coverability problem of {WSTS}},
  journal = 	 {Journal of Computer and System Sciences},
  volume = {72},
  number = {1},
  pages = {180--203},
  year = 	 {2006},
  publisher =    {Elsevier},
  url =          {http://www.ulb.ac.be/di/ssd/ggeeraer/papers/eec-journal.pdf},
}