@article{IM2_2007_71_2_a3,
     author = {A. A. Karatsuba and M. A. Korolev},
     title = {A theorem on the approximation of a trigonometric sum by a shorter one},
     journal = {Izvestiya. Mathematics},
     pages = {341--370},
     year = {2007},
     volume = {71},
     number = {2},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_2007_71_2_a3/}
}