1. Maxwell, J.C.: Phil. Trans. R. Soc. Lond. 155, 459 (1865)
2. Jackson, J.D.: Classical Electrodynamics, 3rd edn. Wiley, New York (1998)
3. Griffiths, D.: Introduction to Elementary Particles, 2nd edn. Wiley, Weiheim (2008)
4. Ryder, L.H.: Quantum Field Theory, 2nd edn. Cambridge University Press, Cambridge (1996)
5. Einstein, A.: Phys. Z. 14, 1261 (1913)