@inproceedings{Horrocks99g,
  title = "Generating Hard Modal Problems for Modal Decision Procedures",
  author = "I. Horrocks and P. F. Patel-Schneider",
  year = "1999",
  booktitle = "Proceedings of the first workshop on Methods for Modalities (M4M-1)",
  key = "Proceedings of M4M1",
  month = "MAY",
  url = "http://www.comlab.ox.ac.uk/people/ian.horrocks/Publications/download/1999/Horrocks99g.pdf",
}