@article{DAN_1984_279_4_a9,
     author = {V. N. Rusak},
     title = {Exact orders of best rational approximations for classes of},
     journal = {Doklady Akademii Nauk},
     pages = {810--812},
     year = {1984},
     volume = {279},
     number = {4},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1984_279_4_a9/}
}