Zhyhallo KM, Zhyhallo TV. On the approximation of functions from the Hölder class given on a segment by their biharmonic Poisson operators. Ukr. Mat. Zhurn. [Internet]. 2019 Jul. 25 [cited 2025 Dec. 5];71(7):915-21. Available from: https://umj.imath.kiev.ua/index.php/umj/article/view/1485