Shkurkin, Dmitry V., et al. “Modernization of the Sphere of Tourist and Hospitality Industry of the South of Russia As a Growth Factor of Socio-Economic Stability of the Region”. International Journal of Economics and Financial Issues, vol. 6, no. 1S, May 2016, pp. 101-6, https://econjournals.com./index.php/ijefi/article/view/2361.