1. E. P. Wigner,Ann. Math. 40, 149 (1939).
2. V. Bargmann and E. P. Wigner,Proc. Nat. Acad. Sci. 34, 211 (1946).
3. E. Cartan,Leçons sur la Théorie des Spineurs II, A. Mercier, ed. (Hermann, Paris, 1939), Arts. 85?86, pp. 87?91.
4. V. Bargmann,Ann. Math. 48, 568 (1947).
5. I. M. Gelfand and M. I. Graev,Izv. Akad. Nauk USSR, Ser. Matem.,17, 189 (1953); English version inAnn. Math. Soc. Transl. 2, 147 (1956).