@article {2003,
	title = {Periodic solutions of nonlinear wave equations with general nonlinearities},
	journal = {Comm.Math.Phys. 243 (2003) no.2, 315},
	number = {SISSA;78/2002/M},
	year = {2003},
	publisher = {SISSA Library},
	doi = {10.1007/s00220-003-0972-8},
	url = {http://hdl.handle.net/1963/1648},
	author = {Massimiliano Berti and Philippe Bolle}
}
