1. K. Abe et al., Phys. Lett. 63B, 239 (1976).
2. R.C. Fernow, American Journal of Physics Vol. 44, No. 6, June 1976.
3. L.G. Ratner et al., Phys. Rev. D15, (1977).
4. A.W. Hendry et al., Phys. Rev. D10, 3662 (1974).
5. C.W. Akerlof et al., Phys. Rev. 5, 1138 (1967).