@article{MZ_1953__58_169340,
     author = {Ernst Witt},
     title = {\"Uber freie {Ringe} und ihre {Unterringe.}},
     journal = {Mathematische Zeitschrift},
     pages = {113--114},
     publisher = {mathdoc},
     volume = {58},
     year = {1953},
     zbl = {0050.02803},
     url = {http://geodesic.mathdoc.fr/item/MZ_1953__58_169340/}
}