[en] Unitary irreducible representations (UIR) of the Lorentz group applied to transform the relativistic three dimensional equations in the momentum space, that describe the interaction of the fermion and the pseudoscalar particle, to the relativistic configurational representation. By help of the addition theorem for the functions, that realize the UIR of the Lorentz group with the nonzero spin, the local potentials in this representation is found. 14 refs