@article {1987,
	title = {Solutions with minimal period for Hamiltonian systems in a potential well.},
	journal = {Ann. Inst. H. Poincare Anal. Non Lineaire 4 (1987), no. 3, 275-296},
	number = {SISSA;79/85/M},
	year = {1987},
	publisher = {SISSA Library},
	url = {http://hdl.handle.net/1963/466},
	author = {Antonio Ambrosetti and Vittorio Coti Zelati}
}
