@article{ELMA_1952__7_140585,
     author = {Hans Ziegler},
     title = {Zum {Begriff} des konservativen {Systems.}},
     journal = {Elemente der Mathematik},
     pages = {121--129},
     publisher = {mathdoc},
     volume = {7},
     year = {1952},
     zbl = {0048.17602},
     url = {http://geodesic.mathdoc.fr/item/ELMA_1952__7_140585/}
}