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Romanyuk, A. S.; Yanchenko, S. Y. Estimates of Approximation Characteristics and Properties of Operators of the Best Approximation for the Classes of Periodic Functions in the Space $B_{1,1}$. Ukr. Mat. Zhurn. 2021, 73 (8), 1102-1119. https://doi.org/10.37863/umzh.v73i8.6755.