Romanyuk AS, Romanyuk VS. Asymptotic estimates for the best trigonometric and bilinear approximations of classes of functions of several variables. Ukr. Mat. Zhurn. [Internet]. 2010Apr.25 [cited 2024Apr.26];62(4):536–551. Available from: https://umj.imath.kiev.ua/index.php/umj/article/view/2886