BABENKO, V. F.; PARFINOVYCH, N. V. Nonsymmetric approximations of classes of periodic functions by splines of defect 2 and Jackson-type inequalities. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 61, n. 11, p. 1443–1454, 2009. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/3113. Acesso em: 5 dec. 2025.