%0 Journal Article %A H. Marcinkowska %T On the differentiability of weak solutions of certain non-elliptic equations %J Studia Mathematica %D 1962 %P 91-107 %V 22 %N 1 %I mathdoc %U http://geodesic.mathdoc.fr/articles/10.4064/sm-22-1-91-107/ %R 10.4064/sm-22-1-91-107 %G en %F 10_4064_sm_22_1_91_107