@article{MAN_1959__137_160671,
     author = {H. R\"USSMANN},
     title = {\"Uber die {Existenz} einer {Normalform} inhaltstreuer elliptischer {Transformationen.}},
     journal = {Mathematische Annalen},
     pages = {64--77},
     publisher = {mathdoc},
     volume = {137},
     year = {1959},
     zbl = {0084.19904},
     url = {http://geodesic.mathdoc.fr/item/MAN_1959__137_160671/}
}