M. A. Al-Sammarraie, L. S. Jaafar Azeez, and A. H. Dheyaa Salman, “Employment of Hotel Classification to Increase Tourist Demand in the Holy Province of Karbala Period 2010-2017”, Utopía y prax. latinoam., vol. 25, no. 1, pp. 407-419, May 2020.