@article{10_4064_cm_74_2_225_238,
     author = {Pawe{\L} Idziak and Andrzej Wro\'nski},
     title = {Definability of principal congruences in equivalential algebras},
     journal = {Colloquium Mathematicum},
     pages = {225--238},
     publisher = {mathdoc},
     volume = {74},
     number = {2},
     year = {1997},
     doi = {10.4064/cm-74-2-225-238},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/cm-74-2-225-238/}
}