NovikovO. A., and RukasovV. I. “Approximation of Classes of Continuous Functions by Generalized De La Vallée-Poussin Sums”. Ukrains’kyi Matematychnyi Zhurnal 47, no. 8 (August 25, 1995): 1069–1079. Accessed July 27, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/5503.