  The massive one-loop {\it QCD} corrections to the production cross sections
of We present the massive one-loop {\it QCD} corrections to the production
cross sections of polarized quarks in the annihilation process $e^+e^-\to
q\bar{q}(g)$ for bottom, top, and charm quarks. From the full analytical
expressions for the production cross sections, Schwinger-type interpolation
formulae for all parity-parity combinations $(VV, V\!A, AA)$ are derived. The
parity-odd interpolation formula contains the correct limit for vanishing quark
masses taking into account a residual coupling of left- and right-chiral states
in the massless theory. Numerical results for the total cross section and the
longitudinal spin polarization demonstrate the accuracy of the interpolation
formulae.
