@article{MAN_1993__296_4_165083,
     author = {T. Koboyashi and H. Pecher and Y. Shibata},
     title = {On a global in time existence theorem of smooth solutions to an nonlinear wave equation with viscosity.},
     journal = {Mathematische Annalen},
     pages = {215--234},
     year = {1993},
     volume = {296},
     number = {4},
     zbl = {0788.35001},
     url = {http://geodesic.mathdoc.fr/item/MAN_1993__296_4_165083/}
}