We obtain a positive solution, a negative solution, and a sign-changing solution for a class of -Laplacian problems with jumping nonlinearities using variational and super-subsolution methods.
"Sign-changing and multiple solutions for the $p$-Laplacian." Abstr. Appl. Anal. 7 (12) 613 - 625, 24 December 2002. https://doi.org/10.1155/S1085337502207010