1. L.D. Landau, E.M. Lifshitz, The Classical Theory of Fields, Course of Theoretical Physics, vol. 2, 4th edn. (Butterworth-Heinemann, Oxford, 1987)
2. J.D. Jackson, Classical Electrodynamics, 3rd edn. (Wiley, Hoboken, 1999)
3. J.C. Maxwell, A Treatise on Electricity & Magnetism (Dover Publications, Mineola, 2003)
4. A. Sommerfeld, Ann. Phys. 337(9), 749 (1910)
5. A. Sommerfeld, Ann. Phys. 338(14), 649 (1910)