1. D. V. Shirkov and I. L. Solovtsov,JINR Rapid Commun.,76, No. 2, 5 (1996); “Analytic QCD running coupling with finite IR behavior and universalα s (0) value,” Preprint hep-ph/9604363 (1996).
2. D. V. Shirkov and I. L. Solovtsov,Phys. Rev. Lett.,79, 1209 (1997); “Analytic model for the QCD running coupling with universalα s (0) value,” Preprint hep-ph/9704333 (1997).
3. G. Källen,Helv. Phys. Acta.,11, 417 (1952).
4. H. Lehmann,Nuovo Cimento,11, 342 (1954).
5. N. N. Bogoliubov and D. V. Shirkov,Introduction to the Theory of Quantum Fields [in Russian], Nauka, Moscow (1984); English transl. prev. ed., Wiley, New York (1959).