@article{DAN_1968_180_6_a4,
     author = {A. A. Karatsuba},
     title = {Sums of characters, and primitive roots, in finite fields},
     journal = {Doklady Akademii Nauk},
     pages = {1287--1289},
     year = {1968},
     volume = {180},
     number = {6},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1968_180_6_a4/}
}