%0 Journal Article %A Leis, Christian %T Hopf-bifurcation in systems with spherical symmetry. I: Invariant tori %J Documenta mathematica %D 1997 %P 61-113 %V 2 %I mathdoc %U http://geodesic.mathdoc.fr/item/DOCMA_1997__2__a11/ %G en %F DOCMA_1997__2__a11