Hembars’ka, S. B., & Zaderei , P. V. (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 - 783. https://doi.org/10.37863/umzh.v74i6.7070