Liu, Hua Ning et Zhang, Wen Peng, Mean Value on the Difference Between a Quadratic Residue and Its Inverse Modulo p, Acta mathematica Sinica. English series (Print) , 23(6), 2007, pp. 915-924
The main purpose of this paper is to use the generalized Bernoulli numbers, Gauss sums and the mean value theorems of Dirichlet L-functions to study the asymptotic property of the difference between a quadratic residue and its inverse modulo p (a prime), and to give an interesting hybrid mean value formula