Imagine the vertex correction diagram in the pseudo-scalar meson theory. The amplitude for this diagram is UV divergent. In order to get rid of this divergence we apply regularization technique and obtain the expression with the UV cut-off parameter. The usual practice is that we expand the result in series and extract the finite part for this expression. In QED this series expansion is performed at zero 3-momenta of participating particles, as the QED coupling constant is obtained from the low-energy experiments. In the pseudo-scalar meson theory the g_piNN coupling constant is obtained at the chyral limit of QCD (m_pi =0). Therefore, I was advised to make renormalization at zero 4-momentum of participating pion. Could annybody here give me some links where the renormalization of pseudo-scalar meson theory is discussed? Your opinion on the question is wellcome.