@article{DAN_1957_116_4_a11,
     author = {P. L. Ul'yanov},
     title = {Permutations within a trigonometric system},
     journal = {Doklady Akademii Nauk},
     pages = {568--571},
     publisher = {mathdoc},
     volume = {116},
     number = {4},
     year = {1957},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1957_116_4_a11/}
}