Zhyhallo TV, Kharkevych YI. Approximating properties of biharmonic Poisson operators in the classes $\hat{L}^{\psi}_{\beta, 1}$ . Ukr. Mat. Zhurn. [Internet]. 2017May25 [cited 2024Apr.28];69(5):650-6. Available from: https://umj.imath.kiev.ua/index.php/umj/article/view/1724