M. A. Al-Sammarraie, L. S. Jaafar Azeez, y 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, n.º 1, pp. 407-419, may 2020.