1. P. A. M. Dirac:Proc. Roy. Soc., A167, 148 (1938).
2. H. A. Lorentz:Enzyklopädie der mathematischen Wissenschaften, Vol.5, No. 14 (Leipzig, 1904).
3. H. A. Lorentz:The Theory of Electrons, 2nd Ed. (New York, N. Y., 1952).
4. J. D. Jackson:Classical Electrodynamics, Chap. 17 (New York, N. Y., 1962).
5. F. Rohrlich:Classical Charged Particles (Reading, Mass., 1965), gives a very through discussion and mathematical treatment of both theories.