@article{GDZPPN00241953X,
title = {On the Wave Equation on a Compact Riemannian Manifold withour Conjugate Points.},
journal = {Mathematische Zeitschrift},
volume = {154},
year = {1977},
pages = {249-276},
zbl = {0341.35052},
url = {http://dml.mathdoc.fr/item/GDZPPN00241953X}
}
Bérard, Pierre H. On the Wave Equation on a Compact Riemannian Manifold withour Conjugate Points.. Mathematische Zeitschrift, Tome 154 (1977) pp. 249-276. http://gdmltest.u-ga.fr/item/GDZPPN00241953X/