@article{Korec1994,
  author    = {{Ivan Korec}},
  title     = {{A Density Estimate for the $3x+1$ Problem}},
  journal   = {{Math. Slovaca}},
  year      = {{1994}},
  volume    = {{44}},
  pages     = {{85--89}},
  url       = {{https://dml.cz/bitstream/handle/10338.dmlcz/133225/MathSlov_44-1994-1_8.pdf}},
  note      = {{MR 95h:11022}},
}