Khongchuary, Wanpen, and Mahasak Ketcham. 2023. “Decision Support System to Analyze the Concentration of the Feed Industry Using Technique of Herfindahl Hirschman Index (HHI)”. Journal of Advanced Development in Engineering and Science 5 (13). Babgkok, Thailand:61-74. https://ph03.tci-thaijo.org/index.php/pitjournal/article/view/839.