@article{10_4064_sm_34_1_17_21,
     author = {R. Kaufman},
     title = {Perfect sets in some groups},
     journal = {Studia Mathematica},
     pages = {17--21},
     publisher = {mathdoc},
     volume = {34},
     number = {1},
     year = {1970},
     doi = {10.4064/sm-34-1-17-21},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/sm-34-1-17-21/}
}