Hembars’ka, S. B., and P. V. Zaderei. 2022. “Best Orthogonal Trigonometric Approximations of the Nikol’skii – Besov-Type Classes of Periodic Functions in the Space $B_{\infty,1}$”. Ukrains’kyi Matematychnyi Zhurnal 74 (6), 772 -83. https://doi.org/10.37863/umzh.v74i6.7070.