@inproceedings{conf/pods/GottlobKS04,
  title = "Conjunctive Queries over Trees",
  author = "Georg Gottlob and Christoph Koch and Klaus U. Schulz",
  year = "2004",
  booktitle = "{Proceedings of the Twenty-third ACM SIGACT-SIGMOD-SIGART Symposium on Principles of Database Systems, June 14-16, 2004, Paris, France}",
  editor = "Alin Deutsch",
  isbn = "1-58113-858-X",
  pages = "189-200",
  publisher = "ACM",
  url = "http://www.acm.org/sigmod/pods/proc04/pdf/P-19.pdf",
  doi = "10.1145/1055558.1055585",
}