@misc{ELMA_1973__28_141090,
     title = {Aufgaben.},
     journal = {Elemente der Mathematik},
     pages = {16--19},
     publisher = {mathdoc},
     volume = {28},
     year = {1973},
     url = {http://geodesic.mathdoc.fr/item/ELMA_1973__28_141090/}
}