1. Y. Tanikawa, Hideki Yukawa: Scientific Works (Iwanami Shoten, Tokyo, 1979).
2. E. P. Wigner, Ann. Math. 40, 149 (1939);
3. V. Bargmann and E. P. Wigner, Proc. Natl. Acad. Scie (U.S.A.) 34, 211 (1948);
4. E. P. Wigner, in Theoretical Physics edited by A. Salam (Intl Atomic Energy Agency, Vienna, 1963).
5. E. Inonu and E. P. Wigner, Proc. Natl. Acad. Sci. (U.S.) 39, 510 (1953).