Prestin J, Savchuk VV, Shydlich AL. Direct and inverse theorems on the approximation of 2π -periodic functions by Taylor – Abel – Poisson operators. Ukr. Mat. Zhurn. [Internet]. 2017May25 [cited 2024Nov.23];69(5):657. Available from: https://umj.imath.kiev.ua/index.php/umj/article/view/1725