Die Fortsetzung stetiger Homomorphismen von $\delta$-Halbgruppen. (German) [The continuation of conitinous homomorphisms of $\delta$-semigroups]. In: Novák, J. (ed.): General Topology and its Relations to Modern Analysis and Algebra. Proceedings of the Third Prague Topological Symposium, 1971. Academia Publishing House of the Czechoslovak Academy of Sciences, Praha, 1972. pp. 401-404