YANCHUK, S. V. On the behavior of solutions of the equation for components of a normal system of differential equations. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 49, n. 10, p. 1436–1440, 1997. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/5142. Acesso em: 7 apr. 2025.