ROMANYUK, A. S.; ROMANYUK, V. S. Asymptotic estimates for the best trigonometric and bilinear approximations of classes of functions of several variables. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 62, n. 4, p. 536–551, 2010. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/2886. Acesso em: 5 dec. 2025.