Roonapai, R., and A.- on Aungsuratana. “Some Factors Effecting the Promotion of Rubber Cropping Program in the Rayong Province”. Kasetsart Journal of Social Sciences, vol. 9, no. 1, Jan. 1988, pp. 25-32, https://so04.tci-thaijo.org/index.php/kjss/article/view/243849.