@article{MAN_1919__79_158794,
     author = {J. Nielsen},
     title = {\"Uber die {Isomorphismen} unendlicher {Gruppen} ohne {Relation}},
     journal = {Mathematische Annalen},
     pages = {269--272},
     publisher = {mathdoc},
     volume = {79},
     year = {1919},
     zbl = {46.0175.02},
     url = {http://geodesic.mathdoc.fr/item/MAN_1919__79_158794/}
}