On the Number of Slopes of the Graph of a Function Defined on a Finite Field

Aart Blokhuis, Simeon Ball, Andries E. Brouwer, Leo Storme, Tamás Szonyi. On the Number of Slopes of the Graph of a Function Defined on a Finite Field. Journal of Combinatorial Theory, Series A, 86(1):187-196, 1999. [doi]