1. F.S. Ham: in Electron Paramagnetic Resonance, ed. by S. Geschwind (Plenum, New York 1972) p. 1–119
2. L.L. Foldy, S.A. Wouthuysen: Phys. Rev. 78, 29 (1950)
3. J.D. Bjorken, S.D. Drell: Relativistic Quantum Mechanics (McGraw- Hill, New York 1964) pp. 45–62
4. M.E. Rose: Elementary Theory of Angular Momentum (Wiley, New York 1957)
5. C. Schwartz: Phys. Rev. 97, 380 (1955)