1. R. Schiller:Phys. Rev.,125, 1100, 1109, 1116 (1962);128, 1402 (1962).
2. In our notationx μ=(x, ict),v μ=dx μ/dτ is the four-velocity, τ is the proper time, andv μ v μ=−c 2.
3. H. A. Kramers:Quantum Mechanics, Sect.57 (Amsterdam, 1957).
4. L. D. Landau andE. M. Lifshitz:Quantum Mechanics, Sect.48 (Reading, Mass., 1958).
5. H. C. Corben:The Classical and Quantum Theories of Spinning Particles, Sect.7, to be published, (San Francisco, 1967).