DRAGOMIR, S. S., and I. FEDOTOV. “AN INEQUALITY OF GRUSS’ TYPE FOR RIEMANN-STIELTJES INTEGRAL AND APPLICATIONS FOR SPECIAL MEANS”. Tamkang Journal of Mathematics 29, no. 4 (December 1, 1998): 287–292. Accessed July 18, 2024. https://journals.math.tku.edu.tw/index.php/TKJM/article/view/4257.