Tangjui, Thapana, Parleda Sampaothong, and Neeyakarn Limaroon. 2022. “The Analysis of COVID-19 impact and the Changes in Revenue Structure of Full Service Carriers: Percentage Change Analysis of Airlines’ Sources of Revenue”. Suan Dusit Graduate School Academic Journal 18 (1). Bankok, Thailand:211-30. https://so19.tci-thaijo.org/index.php/SDUGSAJ/article/view/237.