  Nonlinear waves in a liquid containing gas bubbles are considered in the
three-dimensional case. Nonlinear evolution equation is given for description
of long nonlinear pressure waves. It is shown that in the general case the
equation is not integrable. Some exact solutions for the nonlinear evolution
equation are presented. Application of the Hirota method is illustrated for
finding multi-soliton solutions for the nonintegrable evolution equation in the
three-dimensional case. The stability of the one-dimensional solitary waves is
investigated. It is shown that the one-dimensional solitary waves are stable to
transverse perturbations.
