%0 Journal Article %A Yu. I. Khmelevskii %T Equations in a free semigroup %J Informatics and Automation %D 1971 %P 3-288 %V 107 %I mathdoc %U http://geodesic.mathdoc.fr/item/TRSPY_1971_107_a0/ %G ru %F TRSPY_1971_107_a0