Pishgahifard, Z., & Salehi, H. (2014). Geo-economics and Considerations on the Tourism Industry with Emphasis on Historical Cities Tourism and Ecotourism in Iran. International Journal of Sciences: Basic and Applied Research (IJSBAR), 15(1), 301-310. https://www.gssrr.org/JournalOfBasicAndApplied/article/view/2155