JIEQIONG, Ma; HONGGUANG, Zhu; MIN, Fan. Distribution of heavy metals in pig farm biogas residues and the safety and feasibility assessment of biogas fertilizer. International Journal of Agricultural and Biological Engineering, [S. l.], v. 6, n. 4, p. 35–43, 2013. Disponível em: https://www.ijabe.migration.pkpps06.publicknowledgeproject.org/index.php/ijabe/article/view/1008. Acesso em: 27 feb. 2026.