@article{AIHPC_1989__S6__415_0,
     author = {Mava-Un, J.},
     title = {Forced second order conservative systems with periodic nonlinearity},
     journal = {Annales de l'I.H.P. Analyse non lin\'eaire},
     pages = {415--434},
     publisher = {Gauthier-Villars},
     volume = {S6},
     year = {1989},
     mrnumber = {1204025},
     zbl = {0688.70019},
     language = {en},
     url = {http://archive.numdam.org/item/AIHPC_1989__S6__415_0/}
}