@TechReport{NaumannAIB2007CTR,
  author =       "Uwe Naumann",
  title =        "Call Tree Reversal is NP-Complete",
  institution =  "RWTH Aachen",
  year =         "2007",
  number =       "AIB-2007-18",
  month =        dec,
  url =          "http://aib.informatik.rwth-aachen.de/2007/2007-18.ps.gz",
}