@inproceedings{conf/pods/GottlobK02,
  title = "Monadic Datalog and the Expressive Power of Languages for Web Information Extraction",
  author = "Georg Gottlob and Christoph Koch",
  year = "2002",
  booktitle = "{Proceedings of the Twenty-first ACM SIGACT-SIGMOD-SIGART Symposium on Principles of Database Systems, June 3-5, Madison, Wisconsin, USA}",
  editor = "Lucian Popa",
  pages = "17-28",
  publisher = "ACM",
  url = "http://www.acm.org/sigs/sigmod/pods/proc02/papers/017-GottlobKoch.pdf",
  doi = "10.1145/543613.543617",
}