The Virtual Correction to Bremsstrahlung in High-Energy e+ e-   Annihilation: Comparison of Exact Results
  We have compared the virtual corrections to single hard bremsstrahlung as calculated by S. Jadach, M. Melles, B.F.L. Ward and S.A. Yost to several other expressions. The most recent of these comparisons is to the leptonic tensor calculated by J.H. Kuhn and G. Rodrigo for radiative return. Agreement is found to within a part in 10^5 or better, as a fraction of the Born cross section, for most of the range of photon energies. The massless limits have been shown to agree analytically to NLL order. 
S.A. Yost, C. Glosser, S. Jadach and B.F.L. Ward