BALITINOV, M. A. Some theorems on the behaviour of solutions on the whole for one non-linear system. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 23, n. 1, p. 56–63, 1970. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/8480. Acesso em: 6 dec. 2025.