ZHANG, G.; LI, P. Nonconvex retracts and computation for fixed point index in cones. Topological Methods in Nonlinear Analysis, [S. l.], v. 43, n. 2, p. 365–372, 2016. Disponível em: https://apcz.umk.pl/TMNA/article/view/TMNA.2014.021. Acesso em: 16 apr. 2024.