Kanjanawanawan , S., and S. . . Sahunan. “Production Factors Model in Economics and the Hospitality Industry in Thailand 4.0”. Dusit Thani College Journal, vol. 13, no. 1, Apr. 2020, pp. 369-7, https://so01.tci-thaijo.org/index.php/journaldtc/article/view/241031.