@TechReport{Staiger94,
  author =    "Ludwig Staiger ",
  title =     "Codes, {S}implifying {W}ords, and {O}pen {S}et {C}ondition",
  institution = "RWTH Aachen",
  year =      "1994",
  number =    "AIB-14-1994",
  url =       "http://aib.informatik.rwth-aachen.de/1994/1994-14.ps.gz",
}