@article{MAN_1931__105_159528,
     author = {Th. Estermann},
     title = {Einige {S\"atze} \"uber quadratfreie {Zahlen}},
     journal = {Mathematische Annalen},
     pages = {653--662},
     publisher = {mathdoc},
     volume = {105},
     year = {1931},
     zbl = {57.0222.02},
     url = {http://geodesic.mathdoc.fr/item/MAN_1931__105_159528/}
}