Isolation and Characterization of Soil Fulvic Acid. Pakistan Journal of Analytical & Environmental Chemistry, Pakistan, v. 17, n. 1, p. 8 – 17, 2016. DOI: 10.21743/pjaec/2016.06.002. Disponível em: http://pjaec.pk/index.php/pjaec/article/view/237. Acesso em: 12 jul. 2025.