@article{AUPO_1991__30_1_a2,
     author = {Chajda, Ivan},
     title = {Permutability of congruences in varieties with idempotent operations},
     journal = {Acta Universitatis Palackianae Olomucensis. Facultas Rerum Naturalium. Mathematica},
     pages = {33--37},
     publisher = {mathdoc},
     volume = {30},
     number = {1},
     year = {1991},
     mrnumber = {1166423},
     zbl = {0768.08006},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/AUPO_1991__30_1_a2/}
}