@article{SM_2018_209_5_a1,
     author = {M. A. Korolev},
     title = {New estimate for {a~Kloosterman} sum with primes for a~composite modulus},
     journal = {Sbornik. Mathematics},
     pages = {652--659},
     publisher = {mathdoc},
     volume = {209},
     number = {5},
     year = {2018},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_2018_209_5_a1/}
}