@inproceedings{Horr02c,
  title = "Backtracking and Qualified Number Restrictions: Some Preliminary Results",
  author = "Ian Horrocks",
  year = "2002",
  booktitle = "Proc.\ of the 2002 Description Logic Workshop (DL~2002)",
  pages = "99--106",
  series = "CEUR",
  url = "download/2002/dl02-backtracking.pdf",
  volume = "63",
}