@article{DAN_1958_121_3_a4,
     author = {I. I. Ibragimov},
     title = {Extremum problems in the class of trigonometric polynomials},
     journal = {Doklady Akademii Nauk},
     pages = {415--417},
     publisher = {mathdoc},
     volume = {121},
     number = {3},
     year = {1958},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1958_121_3_a4/}
}