@article{Andaloro2002,
  author    = {{Paul Andaloro}},
  title     = {{The $3X+1$ problem and directed graphs}},
  journal   = {{Fibonacci Quarterly}},
  year      = {{2002}},
  volume    = {{40}},
  pages     = {{43--54}},
  note      = {{MR 2003a:11018}},
}