JANISZEWSKA-WALCZAK, D. Uniqueness of solutions of impulsive hyperbolic differential-functional equations. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 51, n. 2, p. 241–250, 1999. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/4603. Acesso em: 11 apr. 2025.