@misc{ELMA_1971__26_141003,
     title = {Bericht.},
     journal = {Elemente der Mathematik},
     pages = {21--24},
     publisher = {mathdoc},
     volume = {26},
     year = {1971},
     url = {http://geodesic.mathdoc.fr/item/ELMA_1971__26_141003/}
}