GONÇALVES, José Valdo, MARCIAL, Marcos R. and MIYAGAKI, Olimpio H. Topological structure of the solution set of singular equations with sign changing terms under Dirichlet boundary condition. Topological Methods in Nonlinear Analysis. Online. 1 March 2015. Vol. 47, no. 1, pp. 73 - 89. [Accessed 2 July 2025]. DOI 10.12775/TMNA.2015.091.