  The bilinear combination of Dirac spinors $u(p_1,n_1)\bar u(p_2,n_2)$ is
expressed in terms of Lorentz vectors in an explicit covariant form. The fact
that the obtained expression involves only one auxiliary vector makes it very
convenient for analytical computations with REDUCE (or FORM) package in the
helicity formalism. The other advantage of the proposed formulas is that they
are applicable to massive fermions as well as to massless fermions. The
proposed approach is employed for the computation of one-loop Feynman diagrams
and it is demonstrated that it considerably reduces the time of computations.
