Green matrices and continuity of the weak solutions for the elliptic systems with lower order terms

In this paper, we consider the second-order elliptic systems with lower order terms coefficients belonging to Kato-Stummel type classes in a bounded domain Omega subset of R-n, where n >= 3. We establish the existence, global pointwise estimates and L-p estimates for Green matrices. Based on these estimates, we are able to show the continuity of weak solutions for the general elliptic systems by using method of potentials. We also obtain the optimal Schauder estimates for weak solutions.