@TechReport{FernauStaiger94,
  author =    "Henning Fernau and Ludwig Staiger",
  title =     "Valuations and {U}nambiguity of {L}anguages, with {A}pplications to {F}ractal {G}eometry",
  institution = "RWTH Aachen",
  year =      "1994",
  number =    "AIB-22-1994",
  url =       "http://aib.informatik.rwth-aachen.de/1994/1994-22.ps.gz",
}