Konovalov V. N. (1992) “Approximation of functions from the Sobolev space by algebraic polynomials”, Ukrains’kyi Matematychnyi Zhurnal, 44(5), pp. 613-617. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/7956 (Accessed: 6October2024).