@article{JRAM_1957__198_150340,
     author = {Bodo Volkmann},
     title = {Einige {S\"atze} \"uber k-freie {Zahlen.}},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {7--9},
     publisher = {mathdoc},
     volume = {198},
     year = {1957},
     zbl = {0084.04303},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1957__198_150340/}
}