Mathematical morphology and poset geometry. Bretto, Alain, Li Marzi, Enzo Maria (2001) International Journal of Mathematics and Mathematical Sciences
Modal operators on ordered sets Jiří Rachůnek (1985) Acta Universitatis Palackianae Olomucensis. Facultas Rerum Naturalium. Mathematica
MV-algebras with additive closure operators Jiří Rachůnek, Filip Švrček (2000) Acta Universitatis Palackianae Olomucensis. Facultas Rerum Naturalium. Mathematica