@article{10_4064_fm_159_2_153_159,
     author = {Theodore Slaman},
     title = {On a question of {Sierpi\'nski}},
     journal = {Fundamenta Mathematicae},
     pages = {153--159},
     publisher = {mathdoc},
     volume = {159},
     number = {2},
     year = {1999},
     doi = {10.4064/fm-159-2-153-159},
     language = {pl},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/fm-159-2-153-159/}
}