KLEVCHUK, I. I. Bifurcation of an equilibrium state of a singularly perturbed system with lag. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 47, n. 8, p. 1022–1028, 1995. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/5499. Acesso em: 5 dec. 2025.