TRIGUB , R. M. On various moduli of smoothness and $K$-functionals. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 72, n. 7, p. 971–996, 2020. DOI: 10.37863/umzh.v72i7.2384. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/2384. Acesso em: 5 dec. 2025.