XIAO, Jing; NIETO, Juan J.; LUO, Zhiguo. Existence of multiple solutions of some second order impulsive differential equations. Topological Methods in Nonlinear Analysis, [S. l.], v. 43, n. 2, p. 287–296, 2016. Disponível em: https://apcz.umk.pl/TMNA/article/view/TMNA.2014.017. Acesso em: 8 jul. 2025.