@article{PMF_1919_30_1_a2,
     author = {Sierpi\'nski, Wac{\l}aw},
     title = {O pewnem uog\'olnieniu zbior\'ow {Borela}},
     journal = {Prace Matematyczno-Fizyczne},
     pages = {89--94},
     publisher = {mathdoc},
     volume = {30},
     number = {1},
     year = {1919},
     language = {pl},
     url = {http://geodesic.mathdoc.fr/item/PMF_1919_30_1_a2/}
}