Transitive closures of binary relations. III. Václav Flaška, Jaroslav Ježek, Tomáš Kepka (2008) Acta Universitatis Carolinae. Mathematica et Physica
Two closure operators which preserve m-compacticity Jana Ryšlinková, Teo Sturm (1982) Banach Center Publications
Type d'homotopie des treillis et treillis des sous-groupes d'un groupe fini. Jacques Thévenaz, Charles Kratzer (1985) Commentarii mathematici Helvetici