Super-Poincare Covariant Two-Loop Superstring Amplitudes
  The super-Poincare covariant formalism for the superstring is used to compute massless four-point two-loop amplitudes in ten-dimensional superspace. The computations are much simpler than in the RNS formalism and include both external bosons and fermions. 
Nathan Berkovits (IFT-UNESP, Sao Paulo)