VITRYCHENKO, I. E. Critical cases of stability of one nonautonomous essentially nonlinear equation of the nth order. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 49, n. 5, p. 720–724, 1997. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/5054. Acesso em: 5 dec. 2025.