  In this thesis exact results on O(alpha^2) single bremsstrahlung corrections
to low angle Bhabha scattering at LEP/SLC energies are given. The calculation
represents the last outstanding theoretical second order subleading electroweak
contribution for that process, needed to determine the experimental luminosity
at second generation LEP detectors below the 0.1% precision threshold. The
exact, fully differential result is obtained by employing analytical as well as
computer-algebraic methods and includes terms up to O(0.05%) relative to the
Born cross section. The initial output of over 20,000 terms could be reduced to
90, only 18 of which are shown to be numerically relevant and for which a
simple logarithmic ansatz is derived, that is in remarkable agreement with the
complete answer. Strong consistency checks are performed, including
Ward-Takahashi identities and tests on the right infrared limit according to
the Yennie, Frautschi and Suura program. Monte Carlo results for the integrated
cross section are compared with existing calculations in the leading
logarithmic approximation for a chosen set of experimental cuts. The size of
the missing subleading terms is found to be small but non negligible in the
context of setting stringent limits on Standard Model predictions and thus its
realm of validity.
