@TechReport{Steffen91,
  author =    "Bernhard Steffen",
  title =     "Generating {D}ata {F}low {A}nalysis {A}lgorithms from {M}odal {S}pecifications",
  institution = "RWTH Aachen",
  year =      "1991",
  number =    "AIB-31-1991",
  url =       "http://aib.informatik.rwth-aachen.de/1991/1991-31.ps.gz",
}