@article{MZ_1990__203_3_174140,
     author = {Yiming Long},
     title = {Periodic {Solutions} of {Superquadratic} {Hamiltonian} {Systems} with {Bounded} {Forcing} {Terms.}},
     journal = {Mathematische Zeitschrift},
     pages = {453--468},
     publisher = {mathdoc},
     volume = {203},
     number = {3},
     year = {1990},
     zbl = {0666.34045},
     url = {http://geodesic.mathdoc.fr/item/MZ_1990__203_3_174140/}
}