@article{MM2_1991__72_1_155649,
     author = {Zhu Daxin},
     title = {A geometric approach to a result of {Benci} and {Giannoni} for {Hamiltonian} systems with singular potentials.},
     journal = {Manuscripta mathematica},
     pages = {405--414},
     publisher = {mathdoc},
     volume = {72},
     number = {1},
     year = {1991},
     zbl = {0737.58049},
     url = {http://geodesic.mathdoc.fr/item/MM2_1991__72_1_155649/}
}