1. E P Wigner, Göttinger Nachrichten,Math. Nachr. 31, 546 (1932)
2. J P Elliott,Proc. R. Soc. A245, 128 (1958)
3. (Private communication, 1968). cf. L C Biedenharn and P Truini, inElementary particles and the universe, essays in honor of Murray Gell-Mann, edited by John H Schwarz, Cambridge Univ. Press, (Cambridge, 1991) p. 157 ff
4. S Tomonaga,Prog. Theor. Phys. (Jpn)13, 467 (1955) (The promised paper applying this method to three dimensions was never published)
5. R Gilmore,Lie groups, Lie algebras and some of their applications (Wiley, New York, 1974)