@article{Qiu1997,
  author    = {{Wei Xing Qiu}},
  title     = {{Study on $``3x+1"$ problem}},
  journal   = {{J. Shanghai Univ. Nat. Sci. Ed. [Shanghai  da xue xue bao. Zi ran ke xue ban]}},
  year      = {{1997}},
  volume    = {{3}},
  number    = {{4}},
  pages     = {{462--464}},
}