Nakoulima, Ousseynou, Abdennebi Omrane, and Jean Velin. “A Nonlinear Problem for Age-Structured Population Dynamics With Spatial Diffusion”. Topological Methods in Nonlinear Analysis 17, no. 2 (June 1, 2001): 307–319. Accessed January 20, 2022. https://apcz.umk.pl/TMNA/article/view/TMNA.2001.018.