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2. Nagaoka, H. and Sugiura, Y. (1923) Spectroscopic evidence of isotopy. Jpn. J. Phys. 2, 167–278;
3. Nagaoka, H., Sugiura, Y. and Mishima, T. (1924) Isotopes of mercury and bismuth revealed in the satellites of their spectral lines. Nature 113, 459–460.
4. 2) Itakura, K., Kimura, T. and Yagi, E. (1973) Nagaoka Hantaro Den (Biography of H. Nagaoka). supervisor Fujioka, Y., Asahi Shimbun sha, Tokyo (in Japanese).
5. 3) Nagaoka, H. (1904) Kinetics of a system of particles illustrating the line and the band spectrum and the phenomena of radioactivity. Phil. Mag. 7, 445–455.