Multiplicity of positive solutions for a class of quasilinear nonhomogeneous Neumann problems

In this paper we study the existence, nonexistence and multiplicity of positive solutions for nonhomogeneous Neumann boundary value problem of the type -Δpu+λup-1=uqinΩ,u>0inΩ,|∇u|p-2∂u∂η=ϕon∂Ω,where Ω is a bounded domain in Rn with smooth boundary, 1