Al-Majali, Ahmad A., and Radi M. Adayleh. “International Competitiveness in Services in Some Middle East and North Africa Countries Using Gravity Model”. International Review of Management and Marketing 8, no. 2 (March 16, 2018): 53–62. Accessed December 22, 2024. https://econjournals.com/index.php/irmm/article/view/6059.