@article{journals/jacm/GottlobKPS05,
  title = "The complexity of {XPath} query evaluation and {XML} typing",
  author = "Georg Gottlob and Christoph Koch and Reinhard Pichler and Luc Segoufin",
  year = "2005",
  journal = "J. ACM",
  number = "2",
  pages = "284-335",
  volume = "52",
  doi = "10.1145/1059513.1059520",
}