@article{BUMI_1998_8_1B_1_a8,
     author = {D'Ancona, Piero and Spagnolo, Sergio},
     title = {Quasi-symmetrization of hyperbolic systems and propagation of the analytic regularity},
     journal = {Bollettino della Unione matematica italiana},
     pages = {169--185},
     publisher = {mathdoc},
     volume = {Ser. 8, 1B},
     number = {1},
     year = {1998},
     zbl = {0916.35063},
     mrnumber = {732545},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/BUMI_1998_8_1B_1_a8/}
}