SavchukV. V., SavchukM. V., and ChaichenkoS. O. 2019. “Approximation of Bounded holomorphic and Harmonic Functions by Fejér Means”. Ukrains’kyi Matematychnyi Zhurnal 71 (4), 516-42. https://umj.imath.kiev.ua/index.php/umj/article/view/1455.