@article{AM2_1978__17_136723,
     author = {Helmut Karzel},
     title = {Symmetrische {Permutationsmengen.}},
     journal = {Aequationes mathematicae},
     pages = {83--90},
     publisher = {mathdoc},
     volume = {17},
     year = {1978},
     zbl = {0376.20002},
     url = {http://geodesic.mathdoc.fr/item/AM2_1978__17_136723/}
}