@article{IM_1979__52_142650,
     author = {Vieri Benci and Paul H. Rabinowitz},
     title = {Critical {Point} {Theorems} for {Indefinite} {Functionals.}},
     journal = {Inventiones mathematicae},
     pages = {241--274},
     publisher = {mathdoc},
     volume = {52},
     year = {1979},
     zbl = {0465.49006},
     url = {http://geodesic.mathdoc.fr/item/IM_1979__52_142650/}
}