1. Racah G.: ?Theory of Complex Spectra I?, Phys. Rev. 61 (1942), 186?197; II, ibid. 62 (1942), 438?462; III, ibid. 63 (1943), 368?382; IV, ibid. 76 (1949), 1352?1365.
2. Wigner E. P.: ?On the matrices which reduce the Kronecker Products of Representations of S. R. Groups?, 1940, unpublished. Published in L. C. Biedenharn and H.van Dam, (eds.), Quantum Theory of Angular Momentum, Academic Press, New York, 1965, pp. 87?133.
3. Bargmann V.: ?On the Representations of the Rotation Group?, Rev. Mod. Phys. 34 (1962), 829?845.
4. Regge T.: ?Symmetry Properties of Racah's Coefficients?, Nuovo Cim. 11 (1959), 116?117.
5. Biedenharn L. C. and Louck J. D.: Angular Momentum in Quantum Physics, Encyclopedia of Mathematics and Its Applications, Vol. 8; The Racah-Wigner Algebra in Quantum Theory, Vol. 9, edited by G.-C. Rota, Addison-Wesley, Reading, MA, 1981.