@inproceedings{conf/pods/GottlobLS99,
  title = "Hypertree Decompositions and Tractable Queries",
  author = "Georg Gottlob and Nicola Leone and Francesco Scarcello",
  year = "1999",
  booktitle = "{Proceedings of the Eighteenth ACM SIGACT-SIGMOD-SIGART Symposium on Principles of Database Systems, May 31 - June 2, 1999, Philadelphia, Pennsylvania}",
  isbn = "1-58113-062-7",
  pages = "21-32",
  publisher = "ACM Press",
  url = "http://www.informatik.uni-trier.de/~ley/db/conf/pods/GottlobLS99.html",
  doi = "10.1145/303976.303979",
}