  The cross sections for the reaction $e^+ e^- \rightarrow l \bar l q \bar q $
and for similar four fermion production processes at LEP~1, LEP~2 and the NLC
are calculated. Due to the extraordinary symmetry properties of the process,
very compact analytical formulae describe the double differential distributions
in the invariant masses of the $l \bar l$ and $q \bar{q}$ pairs. The total
cross sections may be obtained with two numerical integrations.
