@article{Seifert1988,
  author    = {{Benedict G. Seifert}},
  title     = {{On the arithmetic of cycles for the Collatz-Hasse (`Syracuse') conjectures}},
  journal   = {{Discrete Math.}},
  year      = {{1988}},
  volume    = {{68}},
  pages     = {{293--298}},
  note      = {{MR 89a:11031}},
}