@article{RSMUP_1991__85__201_0,
     author = {Bessi, Ugo},
     title = {Multiple closed orbits for singular conservative systems via geodesic theory},
     journal = {Rendiconti del Seminario Matematico della Universit\`a di Padova},
     pages = {201--215},
     publisher = {Seminario Matematico of the University of Padua},
     volume = {85},
     year = {1991},
     mrnumber = {1142541},
     zbl = {0850.70210},
     language = {en},
     url = {http://www.numdam.org/item/RSMUP_1991__85__201_0/}
}