@article{10_14708_cm_v13i1_5660,
     author = {J. Czajsner},
     title = {Some equivalence relations in relational systems},
     journal = {Commentationes Mathematicae},
     pages = { 81--89},
     publisher = {mathdoc},
     volume = {13},
     number = {1},
     year = {1969},
     doi = {10.14708/cm.v13i1.5660},
     language = {pl},
     url = {http://geodesic.mathdoc.fr/articles/10.14708/cm.v13i1.5660/}
}