@article{IM2_1971_5_2_a3,
     author = {S. A. Stepanov},
     title = {An estimation of {Kloosterman} sums},
     journal = {Izvestiya. Mathematics},
     pages = {319--336},
     year = {1971},
     volume = {5},
     number = {2},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_1971_5_2_a3/}
}