@article{LiLiu2006,
  author    = {{Li, Xiao Chun and Liu, Jun}},
  title     = {{Equivalence of the $3N+1$ and $3N+3k$ conjecture and some related properties}},
  journal   = {{J. Huazhong Univ. Sci. Technol. Nat. Sci.}},
  year      = {{2006}},
  volume    = {{34}},
  number    = {{7}},
  pages     = {{120-121}},
  note      = {{MR 2287654}},
}