@article{1153494551, author = {Hirosawa, Fumihiko}, title = {Loss of regularity for second order hyperbolic equations with singular coefficients}, journal = {Osaka J. Math.}, volume = {42}, number = {1}, year = {2005}, pages = { 767-790}, language = {en}, url = {http://dml.mathdoc.fr/item/1153494551} }
Hirosawa, Fumihiko. Loss of regularity for second order hyperbolic equations with singular coefficients. Osaka J. Math., Tome 42 (2005) no. 1, pp. 767-790. http://gdmltest.u-ga.fr/item/1153494551/