@TechReport{SteffenIngolfsdottir91,
  author =    "Bernhard Steffen and Anna Ingolfsdottir",
  title =     "Characteristic {F}ormulae for {P}rocesses with {D}ivergence",
  institution = "RWTH Aachen",
  year =      "1991",
  number =    "AIB-03-1991",
  url =       "http://aib.informatik.rwth-aachen.de/1991/1991-03.ps.gz",
}