SAMUSENKO, P. F.; SHKII, N. I. On asymptotic formulas for solutions of systems of linear differential equations with a degerate matrix with derivatives. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 48, n. 9, p. 1278–1285, 1996. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/5241. Acesso em: 5 dec. 2025.