Somboonsuke, Buncha, Chaiya Kongmanee, Narisa Thongtrai, and Purawich Phitthayaphinant. 2018. “Potential of Para-Rubber Production in Thailand: Production Technology Management, Problems and Suggestions for Yield Improvement”. Kasetsart Journal of Social Sciences 39 (1):645-59. https://so04.tci-thaijo.org/index.php/kjss/article/view/242476.