Serdyuk, A.; Sorych, V.; Sorych, N. Best Approximation by Trigonometric Polynomials of Convolution Classes Generated by Some Linear Combinations of Periodic Kernels. Ukr. Mat. Zhurn. 2025, 77 (5), 349–363. https://doi.org/10.3842/umzh.v77i5.8934.