Ding, Z., and A. G. Kartsatos. “$p$-Regular Mappings and Alternative Results for Perturbations of $m$-Accretive Operators in Banach Spaces”. Topological Methods in Nonlinear Analysis, vol. 5, no. 2, June 1995, pp. 291-04, https://apcz.umk.pl/TMNA/article/view/TMNA.1995.020.