MARTYNYUK, A. A. On one attribute of solution stability for systems of non-linear differential equations . Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 23, n. 2, p. 253–257, 1971. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/8510. Acesso em: 6 dec. 2025.