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2. “Current Algebras.”;ADLER,1968
3. Charge Superselection Rule
4. BAIRD, G. E., AND BIEDENHARN, L. C. (1964). “Proc. 1st Coral Gables Conf. on Symmetry Principles at High Energy,” p. 58. Freeman, San Francisco.
5. Note on Wigner's Theorem on Symmetry Operations