Keawdounglek, Vivat, Wisakha Phoochinda, and Warangkana Sornil. 2018. “Management Model for Biogas Production from Wastewater of Natural Rubber Processing at Community Level”. Journal of Renewable Energy and Smart Grid Technology 13 (1). https://ph01.tci-thaijo.org/index.php/RAST/article/view/65157.