D. Ismoilov,, A Lower Bound Estimate for Complete Sums of Characters of Polynomials and Rational Functions, Acta Mathematica Sinica, New Series Chinese Journal of Mathematics, 9(1), 1993, pp. 90-99
In this paper we shall study the complete Dirichlet character sums involved with some polynomials and rational functions whichare useful to the Waring's problem.