SMILYANSKY, V. R. Reduction of some systems of ordinary linear differential equations to a simplier form. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 23, n. 6, p. 813–818, 1971. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/8633. Acesso em: 5 dec. 2025.