“…The problem was then studied by Crandall, Rabinowitz and Tartar in [9], where they proved existence of solutions, and continuity properties of the solution if g(x, s) does not depend on x. In 1991, a nice paper by Lazer and McKenna (see [14]) dealt with the case g(x, s) = f (x) u γ , with f a continuous function, proving existence and regularity results at the boundary for the solution; for example, they proved that the solution belongs to H 1 0 ( ) if and only if γ < 3, while it is not in C 1 ( ) if γ > 1 (confront these result with Theorem 4.2 below). The results of Lazer and McKenna were then generalized by Lair and Shaker (see [12] and [13], where the function g is of the form f (x) g(u)), and by Zhang and Cheng (see [18], where the function g is of the form f (x) g(u) and f may not even be in L 1 ( )).…”