@article{1174324326,
author = {Colombini, Ferruccio and Nishitani, Tatsuo},
title = {Second order weakly hyperbolic operators with coefficients sum of powers of functions},
journal = {Osaka J. Math.},
volume = {44},
number = {1},
year = {2007},
pages = { 121-137},
language = {en},
url = {http://dml.mathdoc.fr/item/1174324326}
}
Colombini, Ferruccio; Nishitani, Tatsuo. Second order weakly hyperbolic operators with coefficients sum of powers of functions. Osaka J. Math., Tome 44 (2007) no. 1, pp. 121-137. http://gdmltest.u-ga.fr/item/1174324326/