Zhyhallo KM, Kharkevych YI. Approximation of functions from the classes $C^{\psi}_{\beta, \infty}$ by biharmonic Poisson integrals. Ukr. Mat. Zhurn. [Internet]. 2011Jul.25 [cited 2024Nov.23];63(7):939-5. Available from: https://umj.imath.kiev.ua/index.php/umj/article/view/2776