2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/183976We present a method for symbolic calculation of Feynman amplitudes for processes involving both massless and massive fermions. With this approach fermion strings in a specific amplitude can be easily evaluated and expressed as basic Lorentz scalars. The new approach renders the symbolic calculation of some complicated physical processes more feasible and easier, especially with the assistance of algebra manipulating codes for computer.LaTex, no figure, to appear in PRDHigh Energy Physics - Phenomenologytext