YAKYMIV, R. Ya. On the rate of convergence of the Ritz method for ordinary differential equations. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 52, n. 5, p. 702–706, 2000. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/4463. Acesso em: 6 dec. 2025.