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2. D. P. Zhelobenko, Compact Lie Groups and Their Representations [in Russian], Nauka (1970).
3. P. M. Cohn, Universal Algebra, New York (1965);
4. A. I. Mal'tsev, Algebraic Systems [in Russian], Nauka (1970).
5. P. Stichel, Springer Tracts in Modern Physics, Vol. 50 (1969).