SOLICH, K. V. Estimates for bilinear approximations of the classes TeX of periodic functions of two variables. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 64, n. 8, p. 1106–1120, 2012. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/2644. Acesso em: 5 dec. 2025.