@article{Cadogan1984,
  author    = {{Charles C. Cadogan}},
  title     = {{A note on the $3x +  1$ problem}},
  journal   = {{Caribbean J. Math.}},
  year      = {{1984}},
  volume    = {{3}},
  number    = {{2}},
  pages     = {{69--72}},
  note      = {{MR 87a:11013}},
}