\Bibitem{Tch37} \by N.~Tchudakoff \paper On Weyl's sums \jour Sb. Math. \yr 1937 \vol 44 \issue 1 \mathnet{http://mi.mathnet.ru//eng/sm5559} \zmath{https://zbmath.org/?q=an:0017.10405|63.0153.02}