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r -systems of unary algebras. I: On maximal and greatest J -classes of the direct product of unary algebras Imrich Abrhan, Ladislav Satko (1994) Mathematica Slovaca
Reidemeister- Schreier type rewriting for semigroups. C.M. Campbell, E.F. Robertson, R.M. Thomas, N. Ruskuc (1995) Semigroup forum
Relationship between the inverse transversals of a regular semigroup. T. Saito (1986) Semigroup forum
Remark on one-sided A -ideals of semigroups Hajnal Andréka, István Németi, Robert Šulka (1983) Mathematica Slovaca
Remark on partially ordered sets, universal algebras and semigroups Robert Šulka (1979) Mathematica Slovaca
Representations of semigroups of idempotents Walter S. Sizer (1980) Czechoslovak Mathematical Journal
Right Prime Ideals and Maximal Right Ideals in Semigroups Bedřich Pondělíček (1971) Matematický časopis
Semigroup theoretical approach to normal ideals Tatsuhiko Saito (1987) Beiträge zur Algebra und Geometrie = Contributions to algebra and geometry
Semigroups and rings whose proper one-sided ideals are power joined Alessandra Cherubini, Ada Varisco (1984) Czechoslovak Mathematical Journal