@article{10_4064_aa105_4_4,
     author = {John B. Friedlander and Sergei Konyagin and Igor E. Shparlinski},
     title = {Some doubly exponential sums over ${\Bbb Z}_m$},
     journal = {Acta Arithmetica},
     pages = {349--370},
     publisher = {mathdoc},
     volume = {105},
     number = {4},
     year = {2002},
     doi = {10.4064/aa105-4-4},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/aa105-4-4/}
}