Bodenchuk, V. V., & Serdyuk, A. S. (2015). Exact Values of Kolmogorov Widths for the Classes of Analytic Functions. II. Ukrains’kyi Matematychnyi Zhurnal, 67(8), 1011-1018. https://umj.imath.kiev.ua/index.php/umj/article/view/2041