A Short Remark on the Multiplicative Energy of the Spectrum

An upper bound for the multiplicative energy of the spectrum of an arbitrary subset of Fp\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\mathbb{F}_{p}$$\end{document} is obtained. Apparently, at present, this is the best bound.