Sharif, D. A. ., S. A. Abdullah, B. A. . Othman, and Y. H. . Abdullah. “The Impact of Employee’s Income Grades on Tourism Demand: : An Exploratory Study About Employees Opinion to Their Demand of Tourism in Koya Technical Institute /Iraq”. Polytechnic Journal of Humanities and Social Sciences, vol. 5, no. 1, Feb. 2024, pp. 555-66, doi:10.25156/ptjhss.v5n1y2024.pp555-566.