@article{10_14708_wm_v28i02_4445,
     author = {J. Krempa and Z. Marciniak},
     title = {Pier\'scienie grupowe},
     journal = {Wiadomo\'sci Matematyczne},
     pages = { 137--148},
     publisher = {mathdoc},
     volume = {28},
     number = {02},
     year = {1990},
     doi = {10.14708/wm.v28i02.4445},
     language = {pl},
     url = {http://geodesic.mathdoc.fr/articles/10.14708/wm.v28i02.4445/}
}