%0 Journal Article %A Šlapal, Josef %T On relations %J Czechoslovak Mathematical Journal %D 1989 %P 198-214 %V 39 %N 2 %I mathdoc %U http://geodesic.mathdoc.fr/articles/10.21136/CMJ.1989.102295/ %R 10.21136/CMJ.1989.102295 %G en %F 10_21136_CMJ_1989_102295