DOBBS, D. E. On purity and related universal properties of extensions of commutative rings. Tamkang Journal of Mathematics, [S. l.], v. 41, n. 3, p. 253–259, 2010. DOI: 10.5556/j.tkjm.41.2010.723. Disponível em: https://journals.math.tku.edu.tw/index.php/TKJM/article/view/723. Acesso em: 5 may. 2024.