1. Rational methods in matrix equations;Ingraham, Mark H.;Bull. Amer. Math. Soc.,1941
2. C. C. MacDuffee, The theory of matrices, Ergebnisse der Mathematik und ihrer Grenzgebiete, Chelsea, 1946, pp. 31-36, 81, 89, 94.
3. A. A. Albert, Modern higher algebra, The University of Chicago Science Series, 1937, p. 26.
4. V. J. Varineau, An extension of the theory of matrices with elements in a principal ideal ring, Thǐs paper was submitted as his doctoral dissertation at the University of Wisconsin, July 1940.
5. Left associates of monic matrices, with an application to unilateral matrix equations;Bell, James H.;Amer. J. Math.,1949