Choczewski B, Corovei I, Matkowska A. On some functional equations related to Steffensen’s inequality. Ann. Univ. Paedagog. Crac. Stud. Math. [Internet]. 2004 May 22 [cited 2026 Oct. 30];4:31-7. Available from: https://studmath.uken.krakow.pl/article/view/13306