Ferreira, José Claudinei, and Natally Rodrigues Silva. “About Eigenvalues ​​and Zeros of Polynomials and Optimization Problems: A Synthesis and Demonstrations”. Sigmae, vol. 8, no. 1, Aug. 2019, pp. 1-15, https://publicacoes.unifal-mg.edu.br/revistas/index.php/sigmae/article/view/637.