Nakavetin, A. . ., C. . . Klaysuwan, I. Nawasamrit, S. . . Sukhanthachan, and W. . . Janhom. “Politeness Strategies of Airport Information Staff in Refusing Passengers’ Requests”. Dusit Thani College Journal, vol. 13, no. 1, Apr. 2020, pp. 218-35, https://so01.tci-thaijo.org/index.php/journaldtc/article/view/241014.