@article{Li2006,
  author    = {{Li, Xiao Chun}},
  title     = {{Some properties of super contraction iteration in the $3N+1$ conjecture}},
  journal   = {{J. Huazhong Univ. Sci. Technol. Nat. Sci.}},
  year      = {{2006}},
  volume    = {{34}},
  number    = {{8}},
  pages     = {{115--117}},
  note      = {{MR 2287431}},
}