COWLING, V. F.; THRON, W. J. Zero-Free Regions of Polynomials. The Journal of the Indian Mathematical Society, [S. l.], v. 20, n. 1-3, p. 307–310, 1956. DOI: 10.18311/jims/1956/16997. Disponível em: https://informaticsjournals.com/index.php/jims/article/view/16997. Acesso em: 3 may. 2024.