@article{MM2_1980__33_154752,
     author = {Klaus Thews},
     title = {T-Periodic {Solutions} of {Time} {Dependent} {Hamiltonian} {Systems} with a {Potential} {Vanishing} at {Infinity.}},
     journal = {Manuscripta mathematica},
     pages = {327--338},
     publisher = {mathdoc},
     volume = {33},
     year = {1980},
     zbl = {0467.35009},
     url = {http://geodesic.mathdoc.fr/item/MM2_1980__33_154752/}
}