@article{IM_1993__113_2_144139,
     author = {Michael D. Boshernitzan},
     title = {Quantitative recurrence results.},
     journal = {Inventiones mathematicae},
     pages = {617--632},
     publisher = {mathdoc},
     volume = {113},
     number = {2},
     year = {1993},
     zbl = {0839.28008},
     url = {http://geodesic.mathdoc.fr/item/IM_1993__113_2_144139/}
}