In this paper we settle (in dimension $n=2$) the open question
whether for a divergence form equation $\div (A\nabla u) = 0$ with
coefficients satisfying certain minimal smoothness assumption (a
Carleson measure condition), the $L^p$ Neumann and Dirichlet regularity
problems are solvable for some values of $p\in (1,\infty)$. The related
question for the $L^p$ Dirichlet problem was settled (in any dimension)
in 2001 by Kenig and Pipher [Kenig, C.E. and Pipher, J.: The Dirichlet problem
for elliptic equations with drift terms. Publ. Mat. 45 (2001), no. 1, 199-217].