@article{FAA_2015_49_2_a4,
     author = {S. V. Konyagin and I. D. Shkredov},
     title = {A quantitative version of the {Beurling-Helson} theorem},
     journal = {Funkcionalʹnyj analiz i ego prilo\v{z}eni\^a},
     pages = {39--53},
     publisher = {mathdoc},
     volume = {49},
     number = {2},
     year = {2015},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/FAA_2015_49_2_a4/}
}