@article{GDZPPN002229927,
title = {Multiplicity of Subharmonic solutions of Forces Hamiltonian systems near an equilibrium.},
journal = {Manuscripta mathematica},
volume = {64},
year = {1989},
pages = {389-402},
zbl = {0672.70020},
url = {http://dml.mathdoc.fr/item/GDZPPN002229927}
}
Bertotti, Maria Letizia. Multiplicity of Subharmonic solutions of Forces Hamiltonian systems near an equilibrium.. Manuscripta mathematica, Tome 64 (1989) pp. 389-402. http://gdmltest.u-ga.fr/item/GDZPPN002229927/