YEVSTAFYEVA , V. V. Existence of two-point oscillatory solutions of a relay nonautonomous system with a multiple eigenvalue of a real symmetric matrix. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 73, n. 5, p. 640–650, 2021. DOI: 10.37863/umzh.v73i5.6379. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/6379. Acesso em: 11 apr. 2025.