@article{MZ_1955__62_169502,
     author = {Helmut Salzmann and K. Zeller},
     title = {Singularit\"aten unendlich oft differenzierbarer {Fuktionen.}},
     journal = {Mathematische Zeitschrift},
     pages = {354--367},
     publisher = {mathdoc},
     volume = {62},
     year = {1955},
     zbl = {0064.29903},
     url = {http://geodesic.mathdoc.fr/item/MZ_1955__62_169502/}
}