JournalsaihpcVol. 2, No. 5Volume 2, No. 5 (1985) Annales de l'Institut Henri Poincaré Cpp. 329–370A new degree for S1-invariant gradient mappings and applicationsE.N. Dancerpp. 371–395Heavy viable trajectories of controlled systemsHalina FrankowskaJean-Pierre Aubin