%0 Journal Article %A Salvatore Marano %T Classical solutions of hyperbolic partial differential equations with implicit mixed derivative %J Annales Polonici Mathematici %D 1991 %P 163-178 %V 56 %N 2 %I mathdoc %U http://geodesic.mathdoc.fr/articles/10.4064/ap-56-2-163-178/ %R 10.4064/ap-56-2-163-178 %G en %F 10_4064_ap_56_2_163_178