1. F. J. Yndurain, Theory of Quark and Gluon Interactions, 4th ed. (Springer, Berlin, 2006).
2. B. S. De Witt, Phys. Rev. 162, 1195, 1239 (1967); J. Honerkamp, Nucl. Phys. B 48, 269 (1972); G.’t Hooft, Nucl. Phys. B 62, 444 (1973), Acta Univ. Wratislaviensis 368, 345 (1976); L. F. Abbot, Nucl. Phys. B 185, 189 (1981).
3. Yu. A. Simonov, Yad. Fiz. 58, 113 (1995) [Phys. At. Nucl. 58, 107 (1995)]; hep-ph/9311247, JETP Lett. 57, 513 (1993); Lect. Notes Phys. 479, 139 (1996); A. M. Badalian and Yu. A. Simonov, Phys. At. Nucl. 60, 630 (1997).
4. Yu. A. Simonov, and J. A. Tjon, Ann. Phys. (N.Y.) 300, 54 (2002).
5. A. M. Badalian, B. L. G. Bakker, and Yu. A. Simonov, Phys. Rev. D 75, 116001 (2007).