BUDAK, Hüseyin, and Yonca BAKIȘ. “On Fejér Type Inequalities for Products Convex and S-Convex Functions”. Studia Universitatis Babeș-Bolyai Mathematica, vol. 65, no. 2, June 2020, pp. 165–182, doi:10.24193/subbmath.2020.2.01.