The neutron spectrum equations are investigated for regions in which the neutron source includes both volume and surface components. The results are thereby applicable to reflected cores and reflector regions. The spectrum is analyzed in the volume-integrated P1 approximation. The difference from the corresponding bare-core relations is an additional source, plus the redefinition of the leakage parameter. It is shown, with the approximation of diffusion theory, that the leakage parameter is always nonpositive. Several simplified forms are also developed for this term. A numerical calculation is presented to show the details of the procedure, and the results are compared to a multiregion analysis.