@article{EJDE_2007__2007__a116,
     author = {Tarama, Shigeo},
     title = {Energy estimate for wave equations with coefficients in some {Besov} type class},
     journal = {Electronic Journal of Differential Equations},
     publisher = {mathdoc},
     volume = {2007},
     year = {2007},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/EJDE_2007__2007__a116/}
}