1. 1. S. L. Altmann, Rotations, Quaternions, and Double Groups (University Press, Oxford, 1986).
2. 2. L. C. Biedenharn and H. Van Dam, Quantum Theory of Angular Momentum (Academic, New York, 1965), Paper 1.
3. 3. L. C. Biedenharn and J.D. Louck, Angular Momentum in Quantum Physics (Addison-Wesley, Reading, MA, 1981).
4. 4. L. J. Boya, “State space as projective space,” Found. Phys. 19, 1363–1370 (1989).
5. 5. L. J. Boya and E. C. G. Sudarshan, –Rays and phases in quantum mechanics,” Found. Phys. Lett. 4, 283–287 (1991).