@article{MZ_1939__44_168807,
     author = {S., Selberg},
     title = {Zur {Theorie} der quadratfreien {Zahlen}},
     journal = {Mathematische Zeitschrift},
     pages = {306--318},
     publisher = {mathdoc},
     volume = {44},
     year = {1939},
     zbl = {64.0101.03},
     url = {http://geodesic.mathdoc.fr/item/MZ_1939__44_168807/}
}