Romanyuk, V.S. (1996) “Approximation of classes of analytic functions by algebraic polynomials and kolmogorov widths”, Ukrains’kyi Matematychnyi Zhurnal, 48(2), pp. 236–250. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/5351 (Accessed: 7 April 2025).