@article{AUCMP_1987_28_1_a4,
     author = {Bican, L. and Dr\'apal, A. and Kepka, T.},
     title = {Cancellative relations and matrices},
     journal = {Acta Universitatis Carolinae. Mathematica et Physica},
     pages = {21--31},
     year = {1987},
     volume = {28},
     number = {1},
     mrnumber = {0929263},
     zbl = {0661.20050},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/AUCMP_1987_28_1_a4/}
}