%0 Journal Article %A Terracini, Susanna %T Multiplicity of periodic solution with prescribed energy to singular dynamical systems %J Annales de l'I.H.P. Analyse non linéaire %D 1992 %P 597-641 %V 9 %N 6 %I Gauthier-Villars %U http://www.numdam.org/item/AIHPC_1992__9_6_597_0/ %G en %F AIHPC_1992__9_6_597_0