1. C. Y. Yang and R. L. Mills, 100 Years of Gravity and Accelerated Frames, the Deepest Insights of Einstein and Yang–Mills, eds. J. P. Hsu and D. Fine (World Scientific, 2005) p. 150.
2. R. Utiyama, 100 Years of Gravity and Accelerated Frames, the Deepest Insights of Einstein and Yang–Mills, eds. J. P. Hsu and D. Fine (World Scientific, 2005) p. 157.
3. E. P. Wigner, Symmetries and Reflections, Scientific Essays (MIT Press, 1970) p. 51.
4. F. J. Dyson, 100 Years of Gravity and Accelerated Frames, the Deepest Insights of Einstein and Yang–Mills, eds. J. P. Hsu and D. Fine (World Scientific, 2005) p. 348.
5. YANG–MILLS GRAVITY IN FLAT SPACE–TIME I: CLASSICAL GRAVITY WITH TRANSLATION GAUGE SYMMETRY