VAN, Truong Thi Thuy; ALGHAMDI, Ahmad M.; ALKINANI, Amnah Abdu. On semiperfect $a$-rings. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 76, n. 6, p. 907–914, 2024. DOI: 10.3842/umzh.v76i5.7491. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/7491. Acesso em: 5 dec. 2025.