1. A. Chodos et al., Phys. Rev. D9 3471 (1974) T. de Grand et al., Phys. Rev. D12 2060 (1975)
2. Compare for example: A. de Shalit and H. Feshbach Theoretical Nuclear Physics, J. Wiley and Sons, Inc. (1974)
3. M. Beiner, K. Bleuler, R. de Tourreil, Nuov. Cim. 52B 45
4. H. Weyl, Group Theory and Quantum Mechanics orig. edition: Hirzel Leipzig 1930, compare chapter V
5. N. Jacobson, Lie-algebras, J. Wiley and Sons, New York (1965)