1. V. M. Prokip, "On the solvability of a system of linear equations over the domain of principal ideals," Ukr. Mat. Zh., 66, No. 4, 566-570 (2014)
2. English translation: Ukr. Math. J., 66, No. 4, 633-637 (2014).
3. S. Friedland, Matrices: Algebra, Analysis, and Applications, World Scientific, Singapore (2015).
4. J. A. Green, “On the structure of semigroups,” Ann. Math. Second Series, 54, No. 1, 163–172 (1951); http://www.jstor.org/stable/1969317 .
5. R. E. Hartwig and M. S. Putcha, “Semisimilarity for matrices over a division ring,” Linear Algebra Appl., 39, 125–132 (1981).