Prokip, V. M. “Polynomial Matrices over a Factorial Domain and Their Factorization With Given Characteristic Polynomials”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 50, no. 10, Oct. 1998, pp. 1438–1440, https://umj.imath.kiev.ua/index.php/umj/article/view/4831.