Compact and discrete ring groups
Ring groups were introduced in note  as a generalization of uni-modular groups. In the present note an analogy of Pontrygin's duality theorem for compact and discrete groups is established for ring groups.
Citation Example: Kats G. I. Compact and discrete ring groups // Ukr. Mat. Zh. - 1962. - 14, № 3. - pp. 260-270.