@article{IM2_1973_7_6_a0,
     author = {A. A. Karatsuba},
     title = {The mean value of the modulus of a~trigonometric sum},
     journal = {Izvestiya. Mathematics },
     pages = {1199--1223},
     publisher = {mathdoc},
     volume = {7},
     number = {6},
     year = {1973},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_1973_7_6_a0/}
}