%0 Journal Article %A Zörnig, Pavel %T On difference equations and discrete systems %J Kybernetika %D 1983 %P 225-236 %V 19 %N 3 %I mathdoc %U http://geodesic.mathdoc.fr/item/KYB_1983__19_3_a3/ %G en %F KYB_1983__19_3_a3