Weakly-nonlinear boundary value problems for impulsive systems with small concentrated delays of the argument. Нелінійні коливання, [S. l.], v. 3, n. 1, p. 13–30, 2000. Disponível em: https://twinhead.imath.kiev.ua/index.php/nosc/article/view/91. Acesso em: 22 січ. 2026.