A Litle Note on the Twisted/warped Product Metrics and the Hopf Conjecture. Global Journal of Science Frontier Research, [S. l.], v. 17, n. F6, p. 39–42, 2017. Disponível em: https://www.journalofscience.org/index.php/GJSFR/article/view/2121. Acesso em: 5 feb. 2026.