(1)
Vakarchuk, S. B.; Vakarchuk, M. B. . $K$-Functionals and Extreme Problems of the Theory of Approximation of the Classes of Analytic Functions in a Circle. II. Ukr. Mat. Zhurn. 2022, 74 (7), 921-929. https://doi.org/10.37863/umzh.v74i7.6981.