Chanathaworn, J., and K. Phumivanichakit. “Experimental Co-Digestion of Carbon Rich Source and Earthworm Bedding Wastewater to Improve Bio-Methane Potential Using Experimental Design”. Journal of Renewable Energy and Smart Grid Technology, vol. 13, no. 2, June 2018, https://ph01.tci-thaijo.org/index.php/RAST/article/view/78730.