Two-loop massive fermionic operator matrix elements and intial state QED corrections to e^+e^- \to \gamma^*/Z^*

We describe the calculation of the two–loop massive operator matrix elements for massive external fermions. These matrix elements are needed for the calculation of the $O({\alpha }^2)$ initial state radiative corrections to $e^{+}{e}^{-}$ annihilation into a neutral virtual gauge boson, based on the renormalization group technique.