The existence of three solutions for elliptic Neumann problems with a perturbed nonlinear term depending on two real parameters is investigated. Our approach is based on variational methods.
Gabriele Bonanno. Giuseppina D'Aguì. "Multiplicity Results for a Perturbed Elliptic Neumann Problem." Abstr. Appl. Anal. 2010 1 - 10, 2010. https://doi.org/10.1155/2010/564363