%0 Journal Article %A Král, Jaroslav %T Set-theoretical operations on $k$-multiple languages %J Kybernetika %D 1967 %P 315-320 %V 3 %N 4 %U http://geodesic.mathdoc.fr/item/KYB_1967_3_4_a0/ %G en %F KYB_1967_3_4_a0