Novikova, Olga, Olena Khandii, Larisa Shamileva, Inna Semenenko, and Iaroslav Burko. “Loss Assessment of Qualitative and Quantitative Composition of The Middle Class in Terms of Sustainable and Digital Development”. European Journal of Sustainable Development 10, no. 3 (October 1, 2021): 180. Accessed May 25, 2022. https://www.ecsdev.org/ojs/index.php/ejsd/article/view/1244.