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2. E. D. Nering, Linear Algebra and Matrix Theory, Wiley, New York, 1970, pp. 292–309.
3. S. Warner, Modern Algebra, vol. 2, Prentice-Hall, Englewood Cliffs, New Jersey, 1965, pp. 574–578.
4. H. Weber, Lehrbuch der Algebra, vol. 1, Chelsea, New York. 1963. pp. 135–136.