Putro, L. H. S. . “Emissions of CH4 and CO2 from Wastewater of Palm Oil Mills: A Real Contribution to Increase the Greenhouse Gas and Its Potential As Renewable Energy Sources: 10.32526/Ennrj/20/202100149”. Environment and Natural Resources Journal, vol. 20, no. 1, Nov. 2021, pp. 61-72, https://ph02.tci-thaijo.org/index.php/ennrj/article/view/245510.