@TechReport{Schuerr90,
  author =    {Andy Sch\"urr},
  title =     "{PROGRESS}: {A} {VHL}-{L}anguage {B}ased on {G}raph {G}rammars",
  institution = "RWTH Aachen",
  year =      "1990",
  number =    "AIB-16-1990",
  url =       "http://aib.informatik.rwth-aachen.de/1990/1990-16.ps.gz",
}