Sharp a priori estimates for a quasilinear degenerate elliptic problem

A study is made of the equation
$$\Delta u+\frac1{|x|^\gamma }|u|^{p-2}u=h(x)$$
in a bounded domain $\Omega\subset\mathbb{R}^N$ $(N\ge3)$ with homogeneous Dirichlet boundary conditions.
Here $2<p<\dfrac{2N}{N-2}$ and $2\gamma>2N-(N-2)p$. Sharp best possible a priori estimates are established for the solution of this problem and for its first and second derivatives in the corresponding function spaces.