@article{10_14708_cm_v50i2_5178,
     author = {Marcin Krzywkowski},
     title = {A modified hat problem},
     journal = {Commentationes Mathematicae},
     pages = { 121--126},
     year = {2010},
     volume = {50},
     number = {2},
     doi = {10.14708/cm.v50i2.5178},
     language = {pl},
     url = {http://geodesic.mathdoc.fr/articles/10.14708/cm.v50i2.5178/}
}