AuzingerW. “A Note on Similarity to Contraction for Stable $2 \times 2$ Companion Matrices”. Ukrains’kyi Matematychnyi Zhurnal 68, no. 3 (March 25, 2016): 400-407. Accessed November 25, 2020. http://umj.imath.kiev.ua/index.php/umj/article/view/1847.