@article{MAT_1961_5_2_a10,
     author = {C. L. Siegel},
     title = {\"Uber die {Existenz} einer {Normalform} analytischer {Hamiltonscher} {Differentialgleichungen} in der {N\"ahe} 
},
     journal = {Matematika},
     pages = {129--156},
     publisher = {mathdoc},
     volume = {5},
     number = {2},
     year = {1961},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MAT_1961_5_2_a10/}
}