Chanathaworn, J., C. Thararux, and J. Paoaiang. “Determining Optimization of Factors Affecting Biogas Production by Co-Digestion of Sweet Corncob Waste With Wastewater Using Response Surface Methodology”. Journal of Renewable Energy and Smart Grid Technology, vol. 13, no. 1, May 2018, https://ph01.tci-thaijo.org/index.php/RAST/article/view/65162.