@article{DAN_1978_239_2_a1,
     author = {S. V. Konyagin},
     title = {Approximation properties of arbitrary sets in {Banach} spaces},
     journal = {Doklady Akademii Nauk},
     pages = {261--264},
     publisher = {mathdoc},
     volume = {239},
     number = {2},
     year = {1978},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1978_239_2_a1/}
}