Musienko, A. P., and A. S. Serdyuk. 2013. “Lebesgue-Type Inequalities for the De La Valee-Poussin Sums on Sets of Analytic Functions”. Ukrains’kyi Matematychnyi Zhurnal 65 (4), 522-37. https://umj.imath.kiev.ua/index.php/umj/article/view/2436.