@article{10_21136_CMJ_1975_101358,
     author = {Zelinka, Bohdan},
     title = {Tolerances and congruences on tree algebras},
     journal = {Czechoslovak Mathematical Journal},
     pages = {634--637},
     publisher = {mathdoc},
     volume = {25},
     number = {4},
     year = {1975},
     doi = {10.21136/CMJ.1975.101358},
     mrnumber = {0387099},
     zbl = {0327.08002},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.21136/CMJ.1975.101358/}
}