BABENKO, V. F.; DORONIN, V. G.; LIGUN, A. A.; SHUMEIKO, A. A. On Jackson-Type Inequalities for Functions Defined on a Sphere. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 57, n. 3, p. 291–304, 2005. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/3598. Acesso em: 6 dec. 2025.