%0 Journal Article %A Ibragimov, R.N. %T Approximate equivalence transformations and invariant solutions of a perturbed nonlinear wave equation %J Electronic Journal of Differential Equations %D 2001 %V 2001 %I mathdoc %U http://geodesic.mathdoc.fr/item/EJDE_2001__2001__a175/ %G en %F EJDE_2001__2001__a175