SLYUSARCHUK, V. E. Theorems on instability of systems with respect to linear approximation. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 48, n. 8, p. 1104–1113, 1996. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/5254. Acesso em: 6 dec. 2025.