ROMANYUK, A. S.; ROMANYUK, V. S. Estimates for the best bilinear approximations of the classes $B^r_{p,\theta}$ and singular numbers of integral operators. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 68, n. 9, p. 1240–1250, 2016. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/1917. Acesso em: 11 apr. 2025.