Rukasov VI, Chaichenko SO. Approximation by de la Vallée-Poussin operators on the classes of functions locally summable on the real axis. Ukr. Mat. Zhurn. [Internet]. 2010Jul.25 [cited 2024Nov.23];62(7):968–978. Available from: https://umj.imath.kiev.ua/index.php/umj/article/view/2929