Infinitely many solutions for an elliptic Neumann problem involving critical Sobolev growth

In this paper, we prove the existence of infinitely many solutions for the following elliptic problem with critical Sobolev growth: -Delta u = vertical bar u vertical bar(2)*(-2)u + g(u) in Omega, partial derivative u/partial derivative nu = 0 on partial derivative Omega, where Omega is a bounded domain in R-N with C-3 boundary, N >= 3, nu is the outward unit normal of partial derivative Omega, 2* = 2N/N-2, and g(t) = mu vertical bar t vertical bar(p-2)t - t, or g(t) = mu t, where p is an element of (2, 2*), mu > 0 are constants. We obtain the existence of infinitely many solutions under certain assumptions on N, p and partial derivative Omega. In particular, if g(t) = mu t with mu > 0, N >= 7, and Omega is a strictly convex domain, then the problem has infinitely many solutions. (C) 2011 Published by Elsevier Inc.