1. F. V. Bunkin andA. M. Prokhorov, Polarization Matiere et Rayounement, Volume Jubilaire en l'Bonneur d'Alfred Kastler, Paris (1969);
2. N. G. Basov andN. Krokhin, Seminar at Lebedev Inst., 1969.
3. F. V. Bunkin andA. E. Kazakov,Sov. Phys. Doklady 15 (1971) 758–759.
4. T. W. Kibble,Phys. Rev. 138B (1965) 740–753.
5. W. Heisenberg,Z. Physik 90 (1934) 209–231.