Maroncelli, D., and J. Rodríguez. “On the Solvability of Nonlinear Impulsive Boundary Value Problems”. Topological Methods in Nonlinear Analysis, vol. 44, no. 2, Apr. 2016, pp. 381-98, https://apcz.umk.pl/TMNA/article/view/TMNA.2014.052.