@article{Garner1981,
  author    = {{Lynn E. Garner}},
  title     = {{On the Collatz $3n+1$ algorithm}},
  journal   = {{Proc. Amer. Math. Soc.}},
  year      = {{1981}},
  volume    = {{82}},
  pages     = {{19--22}},
  note      = {{MR 82j:10090}},
}