%0 Journal Article %A M. Giaquinta %A J. Necas %T On the regularity of weak solutions to non linear elliptic systems of partial differential equations. %J Journal für die reine und angewandte Mathematik %D 1980 %P 140-159 %V 316 %I mathdoc %U http://geodesic.mathdoc.fr/item/JRAM_1980__316_152246/ %F JRAM_1980__316_152246