“…u γ+1 2 ∈ W 1,2 0 (Ω). Existence and regularity of solutions of (1.1) with data in suitable Lebesgue space or with measure data are also studied in [18,11,12,35,26,17], while, in case of a nonlinear principal part, we refer to [10,22,33]. We underline also the study of qualitative properties of solutions of (1.1) contained in [13,24].…”