APAKOV, Yu. P. Third boundary-value problem for a third-order differential equation with multiple characteristics. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 70, n. 9, p. 1274–1281, 2018. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/1633. Acesso em: 5 dec. 2025.