Manasyan, M.G. “MAIN ISSUES OF GEOGRAPHICAL RESEARCHES OF SERVICE”. Proceedings of the YSU C: Geological and Geographical Sciences 47, no. 1 (230) (April 13, 2013): 36–42. Accessed November 24, 2024. https://pub.ysu.am/index.php/proceedings-geol-geogr/article/view/vol47_no1_2013_pp036-042.