Dzyubenko, H. A. “Almost Coconvex Approximation of Continuous Periodic Functions”. Ukrains’kyi Matematychnyi Zhurnal 71, no. 3 (March 25, 2019): 353–367. Accessed April 26, 2025. https://umj.imath.kiev.ua/index.php/umj/article/view/1444.