About one method of analytical calculations of reaction amplitudes with   fermions
  The paper presents the new method of calculations of reaction amplitudes of processes with spin 1/2 fermions. The method is based on the application of isotropic tetrad in Minkowski space and basis spinors connected with it. We obtained as test and illustration of the method the amplitudes of interaction processes $e^-e^+\to f \bar{f} $, $e^- e^+\to W^-W^+ $ and one of the possible diagrams of the process $e^+e^-\to e^+e^-e^+e^-e^+e^-$. 
V.V. Andreev (Gomel State University)