1. Barut, A.O., Božić, M., Marić, Z., Rauch, H.: Z. Phys. A — Atomic Nuclei328, 1 (1987)
2. Barut, A.O.: In: Structure of matter. Proceedings of the Rutherford Centennary Conference. University of Christchurch Press 1971; J. Math. Phys.21, 568 (1980)
3. Aydin, Z.Z., Barut, A.O., Duru, I.H.: Phys. Rev. D26, 1794 (1982); D28, 2872 (1983)
4. Beg, M.A., Marciano, W.J., Ruderman, M.: Phys. Rev. D17, 1395 (1977)
5. Voloshin, M.B., Vysotskii, M.I., Okun', L.B.: ŽЭTΦ91, 754 (1986)