Does anyone know this result?
Let $A$ be a matrix symmetric matrix such that $\lambda I \le A(x) \le \Lambda I$ where $I$ is the identity and $v$ is a solution of $ \mbox{div}(A(x)\nabla v) = 0 $ in $B_R \subset \mathbb{R^{n}}$. Then for some constant $0<\alpha<1$ we have $ \int_{B_r} | \nabla v - (\nabla v)_r|^{2}dx \le C(\lambda, \Lambda)\Bigl( \dfrac{r}{R}\Bigr)^{n - 2 + 2\alpha} \int_{B_r}| \nabla v(x) -(\nabla v)_{R}|^{2}dx $ for any $0
If you know this result or result similar, or you know some reference for this, please tell me.