Existence of entropy solutions for some nonlinear problems in Orlicz spaces

We study in the framework of Orlicz Sobolev spaces W01LM(Ω), the existence of entropic solutions to the nonlinear elliptic problems: −div a(x,u,∇u)+div Φ(u)=f in Ω, for the case where the second member of the equation f∈L 1(Ω), and Φ∈(C0(ℝ))N