Jp. Gossez et P. Omari, ON A SEMILINEAR ELLIPTIC NEUMANN PROBLEM WITH ASYMMETRIC NONLINEARITIES, Transactions of the American Mathematical Society, 347(7), 1995, pp. 2553-2562
We consider the Neumann problem (1.1) below. We extend the range of ap
plicability of the sharp nonresonance condition derived in [Go-Om] so
as, in particular, allow asymmetric nonlinearities.