@article{ELMA_1961__16_140722,
     author = {E. Trost},
     title = {Ungel\"oste {Probleme.}},
     journal = {Elemente der Mathematik},
     pages = {13--13},
     year = {1961},
     volume = {16},
     url = {http://geodesic.mathdoc.fr/item/ELMA_1961__16_140722/}
}