@misc{ELMA_1968__23_140900,
     title = {Aufgaben.},
     journal = {Elemente der Mathematik},
     pages = {111--115},
     publisher = {mathdoc},
     volume = {23},
     year = {1968},
     url = {http://geodesic.mathdoc.fr/item/ELMA_1968__23_140900/}
}