@article{MAN_1992__293_4_164974,
     author = {Thomas Bartsch and M\'onica Clapp},
     title = {The compact category and mulitple periodic solutions of {Hamiltionian} systems on symmetric starshaped energy surfaces.},
     journal = {Mathematische Annalen},
     pages = {523--542},
     publisher = {mathdoc},
     volume = {293},
     number = {4},
     year = {1992},
     zbl = {0735.58029},
     url = {http://geodesic.mathdoc.fr/item/MAN_1992__293_4_164974/}
}