%0 Journal Article
%A Carlo Greco
%T Periodic trajectories of a class of Lorentz-metrics of a time-dependent gravitational field.
%J Mathematische Annalen
%D 1990
%P 515-522
%V 287
%N 1
%I mathdoc
%U http://geodesic.mathdoc.fr/item/MAN_1990__287_1_164701/
%F MAN_1990__287_1_164701