BABENKO, V. F.; LEIS, Azar. The best $L_1$-approximations of classes of functions defined by differential operators in terms of generalized splines from these classes. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 50, n. 11, p. 1443–1451, 1998. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/4796. Acesso em: 11 apr. 2025.