@article{CMH_1990__65_3_140179,
     author = {L.H. Eliasson},
     title = {Normal forms for {Hamiltonian} systems with {Poisson} commuting integrals - elliptic case.},
     journal = {Commentarii mathematici Helvetici},
     pages = {4--35},
     publisher = {mathdoc},
     volume = {65},
     number = {3},
     year = {1990},
     zbl = {0702.58024},
     url = {http://geodesic.mathdoc.fr/item/CMH_1990__65_3_140179/}
}