@article{oai:repository.dl.itc.u-tokyo.ac.jp:00040081,
 author = {Colombini, Ferruccio and Del, Santo  Daniele},
 issue = {1},
 journal = {Journal of mathematical sciences, the University of Tokyo},
 month = {Jun},
 pages = {95--111},
 title = {A note on hyperbolic operators with Log-Zygmund coefficients},
 volume = {16},
 year = {2009}
}