@unpublished{arXiv:0802.2228v1,
  author = "Stephan Kreutzer and Sebastian Ordyniak",
  note = "Preprint. Slightly revised version of arXiv.org (no arXiv:0802.2228v1)",
  title = "Digraph Decompositions and Monotonocity in Digraph Searching",
  url = "http://web.comlab.ox.ac.uk/oucl/work/stephan.kreutzer/Publications/08-digraph-searching-preprint.pdf",
  year = "2008",
}