Characteristic functions freely generate measurable functions Denis Higgs (1981) Fundamenta Mathematicae
On automorphism groups of relational systems and universal algebras J. Płonka (1979) Colloquium Mathematicae
On locally small based algebraic theories Jan Reiterman (1986) Commentationes Mathematicae Universitatis Carolinae
On minimization theorems for polyadic groups H-derived from groups Jacek Michalski (1991) Beiträge zur Algebra und Geometrie = Contributions to algebra and geometry
On surjective kernels of partial algebras. Zlatoš, P. (1992) Acta Mathematica Universitatis Comenianae. New Series