@article{SM_2006_197_4_a1,
     author = {V. I. Danchenko},
     title = {Estimates of  derivatives of simplest fractions and other questions},
     journal = {Sbornik. Mathematics},
     pages = {505--524},
     publisher = {mathdoc},
     volume = {197},
     number = {4},
     year = {2006},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_2006_197_4_a1/}
}