“…However, several special cases have been studied (O'Doherty and Anstey, 1971;Kopnichev, 1977;Toks6z, 1977, 1981;Richards and Menke, 1983;and Gao et al, 1983a, b). Wu (1984Wu ( , 1985 formulated the multiple scattering problem in the frequency domain using radiative transfer theory.…”