@article{MASLO_1994__44_1_a7,
     author = {Korec, Ivan},
     title = {A density estimate for the $3x+1$ problem},
     journal = {Mathematica slovaca},
     pages = {85--89},
     publisher = {mathdoc},
     volume = {44},
     number = {1},
     year = {1994},
     mrnumber = {1290275},
     zbl = {0797.11027},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/MASLO_1994__44_1_a7/}
}