Zhyhallo KM, Kharkevych YI. On the Approximation of Functions of the Hölder Class by Triharmonic Poisson Integrals. Ukr. Mat. Zhurn. [Internet]. 2001Jun.25 [cited 2024May11];53(6):855-9. Available from: https://umj.imath.kiev.ua/index.php/umj/article/view/4306