@TechReport{Cachat01,
  author =       "Thierry Cachat",
  title =        "The power of one-letter rational languages",
  institution =  "RWTH Aachen",
  year =         "2001",
  number =       "AIB-03-2001",
  month =        march,
  url =          "http://aib.informatik.rwth-aachen.de/2001/2001-03.ps.gz",
  keywords =     "rationality, one-letter languages, integers, power
                  operation, divisibility",
}