Rybalchenko, N., S. Bilohur, R. Oleksenko, V. Voronkova, and I. Verkhovod. “Clasterization Tendences of Ukraine’s Tourism Sphere and Way Out of the COVID-19 Pandemic Crisis”. Journal of the University of Zulia , Vol. 12, no. 34, Aug. 2021, pp. 60-75, doi:10.46925//rdluz.34.05.