Principal congruence relations and principal tolerances on varieties of lattices Jaromír Duda (1989) Mathematica Slovaca Similarity:
A principal congruence identity characterizing the variety of distributive lattices with zero Ivan Chajda (1990) Mathematica Slovaca Similarity:
Varieties with modular and distributive lattices of symmetric or reflexive relations Ivan Chajda (1992) Czechoslovak Mathematical Journal Similarity: