@article{MZ_1951__55_169261,
     author = {Otto Gr\"un},
     title = {\"Uber ungerade vollkommene {Zahlen.}},
     journal = {Mathematische Zeitschrift},
     pages = {353--354},
     year = {1951},
     volume = {55},
     zbl = {0046.27107},
     url = {http://geodesic.mathdoc.fr/item/MZ_1951__55_169261/}
}