@article{DOCMA_1997__2__a11,
     author = {Leis, Christian},
     title = {Hopf-bifurcation in systems with spherical symmetry. {I:} {Invariant} tori},
     journal = {Documenta mathematica},
     pages = {61--113},
     publisher = {mathdoc},
     volume = {2},
     year = {1997},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/DOCMA_1997__2__a11/}
}