  The present note establishes the self-averaging, radiative transfer limit for
the two-frequency Wigner distribution for classical waves in random media.
Depending on the ratio of the wavelength to the correlation length the limiting
equation is either a Boltzmann-like integral equation or a Fokker-Planck-like
differential equation in the phase space. The limiting equation is used to
estimate three physical parameters: the spatial spread, the coherence length
and the coherence bandwidth. In the longitudinal case, the Fokker-Planck-like
equation can be solved exactly.
