Fedunyk-Yaremchuk, O. and Hembars’ka, S. 2022. Best orthogonal trigonometric approximations of the Nikol’skii-Besov-type classes of periodic functions of one and several variables. Carpathian Mathematical Publications. 14, 1 (Jun. 2022), 171–184. DOI:https://doi.org/10.15330/cmp.14.1.171-184.