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4. For a recent review see K. Sundermeyer,Lecture Notes in Physics 169, Springer-Verlag, N. Y., 1982, where further references to the original works can be found. See alsoRelativistic Action at a Distance: Classical and Quantum Aspects, Lecture Notes in Physics 162, J. Llosa (ed.), Springer-Verlag, Berlin, 1982.
5. Gotay, AM., and Nester, AJ. M.,Ann. Inst. H. Poincar� 30, 129 (1979).