1. See e.g. Dyson F. J.: Symmetry Groupsin Nuclear and Particle Physics. W. A. Benjamin, Inc. New York 1966;
2. Spectroscopic and Group-theoretical Methods in Physics. Ed. by F. Bloch, S. G. Cohen, A. de Shalit, S. Sambursky, XX Talmi. North Holland Publ. Co., Amsterdam 1968;
3. Moshinsky M.: Rev. Mod. Phys.34 (1962), 813;
4. Lipkin's lecture in Proc. of the Heidelberg Internat. Conf. on Elementary Particles. Ed. by H. Filthuth, North-Holland Publ. Co., Amsterdam 1968.
5. Gel'fand I. M., Zetlin M. L.: Dokl. Akad. Nauk SSSR71 (1950), 825 (in Russian).