@Misc{gekakaosscth08b,
  author =	 "M. Gebser and R. Kaminski and B. Kaufmann and M. Ostrowski
                  and T. Schaub and S. Thiele",
  title =	 "A User's Guide to gringo, clasp, clingo, and iclingo",
  howpublished = "Unpublished draft",
  year =	 2008,
  note =	 "Available at URL\footnote{\texttt{http://downloads.sourceforge.net/potassco/guide.pdf?use\_mirror=}}"
}