@article{01184306, title = {Wave equations with low regularity coefficients.}, journal = {Documenta Mathematica}, year = {1998}, pages = {723-730}, zbl = {0909.35081}, language = {en}, url = {http://dml.mathdoc.fr/item/01184306} }
Smith, Hart F. Wave equations with low regularity coefficients.. Documenta Mathematica, (1998), pp. 723-730. http://gdmltest.u-ga.fr/item/01184306/