%0 Journal Article %A H. Renelt %T An integral formula for the derivatives of solutions of certain elliptic systems %J Annales Polonici Mathematici %D 1991 %P 45-57 %V 54 %N 1 %I mathdoc %U http://geodesic.mathdoc.fr/articles/10.4064/ap-54-1-45-57/ %R 10.4064/ap-54-1-45-57 %G en %F 10_4064_ap_54_1_45_57