C. LARINO, Ranel; M. CASTAÑARES, Josephine. The Effect of Pulang-Bato Spring on the Levels of Copper and Zinc at the Zone of Impact of the Spring and a Section of Butuanon River. International Journal of Sciences: Basic and Applied Research (IJSBAR), Jordan, v. 48, n. 6, p. 82–107, 2019. Disponível em: https://gssrr.org/JournalOfBasicAndApplied/article/view/10337. Acesso em: 2 oct. 2025.