1. T. Damhus, On the existence of real Clebsch-Gordon coefficients, to be published in J. Math. Phys.
2. Über die reelen Darstellungen der endlichen Gruppen;Frobenius;S.-B. Königl. Preuss. Akad.,1906
3. Character Theory of Finite Group;Isaacs,1976
4. Characters of Finite Groups;Feit,1967
5. Elements of the Theory of Representations;Kirillov,1976