Finite binary relations have no more complexity than finite semigroups. John Rhodes (1974) Semigroup forum
Finitely generated left commutative semigroups are residually finite. T. Nordahl (1984) Semigroup forum
Finitely generated left distributive semigoups Tomáš Kepka, Abdullah Zejnullahu (1989) Acta Universitatis Carolinae. Mathematica et Physica
Finiteness of lattices of congruences on commutative semigroups. T. Tamura, T.E. Nordahl (1972) Semigroup forum
Flatness Properties of Monocyclic Acts. S. Bulman-Fleming, P. Normak (1996) Monatshefte für Mathematik
Free left distributive semigroups Abdullah Zejnullahu (1989) Acta Universitatis Carolinae. Mathematica et Physica
Fundamental order relations on inverse semigroups and on their generalizations. Simon M. Goberstein (1980) Semigroup forum
Fuzzy ideals extensions of ordered semigroups. Xie, Xiang-Yun, Yan, Feng (2005) Lobachevskii Journal of Mathematics