Stepanets, O. I., and A. L. Shydlich. “On Some Properties of Convex Functions”. Ukrains’kyi Matematychnyi Zhurnal 59, no. 7 (July 25, 2007): 920–938. Accessed April 25, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/3357.