PAFYK, S. P.; YAKOVETS, V. P. On the structure of the general solution and conditions of solvability of the Cauchy problem for degenerate linear systems of higher-order differential equations. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 65, n. 2, p. 296–305, 2013. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/2419. Acesso em: 5 dec. 2025.