@article{DAN_1961_139_3_a2,
     author = {M. M. Dragilev},
     title = {The order of the best approximation by linear combinations of elements of an extended basis to functions defined on a continuum},
     journal = {Doklady Akademii Nauk},
     pages = {528--530},
     publisher = {mathdoc},
     volume = {139},
     number = {3},
     year = {1961},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1961_139_3_a2/}
}