Levin Conjecture for Group Equations of Length 9. European Journal of Pure and Applied Mathematics, Maryland, USA, v. 13, n. 4, p. 914–938, 2020. DOI: 10.29020/nybg.ejpam.v13i4.3786. Disponível em: https://www.ejpam.com/index.php/ejpam/article/view/3786.. Acesso em: 30 apr. 2024.