%0 Journal Article %A V. I. Astakhov %T Additivity of the Space of Densities of Simple-Layer Potentials with a Finite Dirichlet Integral and Integrability of Normal Derivatives of Harmonic $W_2^1$-Functions on Lipschitz Surfaces %J Matematičeskie zametki %D 2011 %P 659-664 %V 90 %N 5 %I mathdoc %U http://geodesic.mathdoc.fr/item/MZM_2011_90_5_a1/ %G ru %F MZM_2011_90_5_a1