Fetisova, Olga Vladimirovna, et al. “Progressive Areas of Developing Transforming Factors of Tourism and Recreational Cluster of the Volgograd Region”. International Journal of Economics and Financial Issues, vol. 6, no. 2S, June 2016, pp. 65-73, https://econjournals.net.tr/index.php/ijefi/article/view/2533.