@article{MZ_1994__216_4_174660,
     author = {J\"urgen Moser},
     title = {On quadratic symplectic mappings.},
     journal = {Mathematische Zeitschrift},
     pages = {417--430},
     publisher = {mathdoc},
     volume = {216},
     number = {4},
     year = {1994},
     zbl = {0806.58024},
     url = {http://geodesic.mathdoc.fr/item/MZ_1994__216_4_174660/}
}