ZATORSKY, R.A. Researching of Hessenberg’s matrix functions. Carpathian Mathematical Publications, [S. l.], v. 3, n. 1, p. 49–55, 2011. Disponível em: https://ktipe.pnu.edu.ua/index.php/cmp/article/view/3086. Acesso em: 17 may. 2025.