Partial orders and their semigroups of closed relations. D.W. Hardy, M.C. Thornton (1982) Semigroup forum
Productive representations of semigroups by pairs of structures Věra Trnková (1977) Commentationes Mathematicae Universitatis Carolinae
Products of metric, uniform and topological spaces Věra Trnková (1990) Commentationes Mathematicae Universitatis Carolinae
Products of topological spaces represent any semigroup (Preliminary communication) Věra Trnková (1975) Commentationes Mathematicae Universitatis Carolinae