M. Sachs andS. L. Schwebel:Suppl. Nuovo Cimento,21, 197 (1961).
S. L. Schwebel: (to be published);S. L. Schwebel andM. Sachs:Bull. Am. Phys. Soc.,5, 505 (1960).
A. Schupp, R. Pidd andH. Crane:Phys. Rev.,121, 1 (1961).
M. Sachs andS. L. Schwebel:Journ. Math. Phys.,3, 843 (1962).
J. Jauch andR. Rohrlich:The Theory of Photons and Electrons (Cambridge, Mass., 1955).
E. Hill:Rev. Mod. Phys.,23, 253 (1951)P. Roman:Theory of Elementary Particles, Chapt. IV (Amsterdam, 1960).
W. Gordon:Zeits. Phys.,50, 630 (1928).
W. Panofsky andM. Phillips:Classical Electricity and Magnetism (Reading, Mass., 1955).