@inproceedings{frisch:Multiset,
  author = "Frisch, A.M. and Miguel, I. and Kiziltan, Z. and Hnich, B.
            and Walsh, T.",
  title = "Multiset Ordering Constraints",
  booktitle = "Proceedings of the Eighteenth International Joint Conference
               on Artificial Intelligence",
  editor = "Gottlob, G.",
  pages = {318--332},
  year = 2003}