@article{1153492777,
author = {Dreher, Michael},
title = {Weakly hyperbolic equations, Sobolev spaces of variable order, and propagation of singularities},
journal = {Osaka J. Math.},
volume = {39},
number = {1},
year = {2002},
pages = { 409-445},
language = {en},
url = {http://dml.mathdoc.fr/item/1153492777}
}
Dreher, Michael. Weakly hyperbolic equations, Sobolev spaces of variable order, and propagation of singularities. Osaka J. Math., Tome 39 (2002) no. 1, pp. 409-445. http://gdmltest.u-ga.fr/item/1153492777/