@article{MZM_1998_64_3_a15,
     author = {A. A. Karatsuba},
     title = {An estimate of the $L_1$-norm of an exponential sum},
     journal = {Matemati\v{c}eskie zametki},
     pages = {465--468},
     publisher = {mathdoc},
     volume = {64},
     number = {3},
     year = {1998},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1998_64_3_a15/}
}