@article{SnappTracy2008,
  author    = {{Bart Snapp and Matt Tracy}},
  title     = {{The Collatz problem and Analogues}},
  journal   = {{J. Integer Sequences}},
  year      = {{2008}},
  volume    = {{11}},
  note      = {{Article 08.4.7, 10pp. (MR 2009i:11144)}},
}