@article{AA_2007_19_2_a6,
     author = {A. L. Lukashov},
     title = {Estimates for derivatives of rational functions and the fourth {Zolotarev} problem},
     journal = {Algebra i analiz},
     pages = {122--130},
     publisher = {mathdoc},
     volume = {19},
     number = {2},
     year = {2007},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AA_2007_19_2_a6/}
}