@article{10_21136_CMJ_1989_102309,
     author = {Niederle, Josef},
     title = {Conditions for transitive principal tolerances},
     journal = {Czechoslovak Mathematical Journal},
     pages = {380--381},
     publisher = {mathdoc},
     volume = {39},
     number = {2},
     year = {1989},
     doi = {10.21136/CMJ.1989.102309},
     mrnumber = {992141},
     zbl = {0686.08003},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.21136/CMJ.1989.102309/}
}