@article{DAN_1963_151_1_a15,
     author = {L. P. Usol'tsev},
     title = {On an exponential rational trigonometric sum of special type},
     journal = {Doklady Akademii Nauk},
     pages = {62--64},
     publisher = {mathdoc},
     volume = {151},
     number = {1},
     year = {1963},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1963_151_1_a15/}
}