Solution regularity and co-normal derivatives for elliptic systems with non-smooth coefficients on Lipschitz domains

Elliptic PDE systems of the second order with coefficients from L∞L∞ or Hölder–Lipschitz spaces are considered in the paper. Continuity of the operators in corresponding Sobolev spaces is stated and the internal (local) solution regularity theorems are generalized to the non-smooth coefficient case. For functions from the Sobolev space Hs(Ω)Hs(Ω), 12