Monoenergetic neutron transport without multiplication is considered in an infinite homogeneous medium with an arbitrarily anisotropic scattering law. Defining the effective source strength as the parameter β which appears in the asymptotic total flux due to an isotropic plane source of unit strength localized at x = 0, γo being the inverse diffusion length and a the ratio of absorption to total macroscopic cross sections, we have shown that in the series expansion of β in powers of the absorption parameter a, the coefficients βm depend only on the first m + 1 Legendre moments of the scattering probability.