“…Such problems have been studied extensively in the context of Dirichlet equations. In this direction, we mention the works of Costa and Silva [8], Hirano and Nishimura [14], Landesman et al [20], Liang and Su [22], Liu [24], Li and Su [25], Li and Zou [26], Su and Tang [34], Zou [37], and Zou and Liu [38]. For the corresponding Neumann problem, the bibliography is not that rich.…”