@article{DAN_1968_183_6_a4,
     author = {G. I. Natanson},
     title = {Certain cases when {Fourier} sums give best order approximation},
     journal = {Doklady Akademii Nauk},
     pages = {1254--1257},
     publisher = {mathdoc},
     volume = {183},
     number = {6},
     year = {1968},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1968_183_6_a4/}
}