@article{MAN_1995__301_4_165300,
     author = {T. Branson and G. Olafsson},
     title = {Huyghens' principle in {Riemannian} symmetric spaces.},
     journal = {Mathematische Annalen},
     pages = {445--462},
     publisher = {mathdoc},
     volume = {301},
     number = {4},
     year = {1995},
     zbl = {0822.43002},
     url = {http://geodesic.mathdoc.fr/item/MAN_1995__301_4_165300/}
}