Sittivoradet, Pattamavadee, and Ratchaphon Suntivarakorn. 2013. “An Appropriate Approach for Biogas Production and Utilization from Waste Food and Animal Manure in Khon Kaen University”. Engineering and Applied Science Research 40 (1):35-46. https://ph01.tci-thaijo.org/index.php/easr/article/view/8565.