1. De Broglie, L., Bohm, D., Hillion, P., Halbwachs, F., Takabayasi, T., and Vigier, J. P., Phys. Rev. 129 (1963), 438.
2. See also Bohm, D. and Vigier, J. P., Phys. Rev. 109 (1958), 1882
3. Takabayasi, T., Prog. Theor. Phys. 23 (1960), 915
4. Prog. Theor. Phys. Suppl. Extra Number (1965), 339.
5. Hara, O. and Goto, T., Prog. Theor. Phys. Suppl. No. 41 (1968), 56.