@inproceedings{Cadogan1991,
  author    = {{Charles C. Cadogan}},
  title     = {{Some observations on the $3x+1$ problem}},
  booktitle = {{Proc. Sixth Caribbean Conference on Combinatorics & Computing}},
  publisher = {{University of the West Indies: St. Augustine Trinidad}},
  year      = {{1991}},
  pages     = {{84--91}},
}