Chkhartishvili, A.G. et al. 2021. Face Mask Perception during the COVID-19 Pandemic: an Observational Study of Russian Online Social Network VKontakte. Advances in Systems Science and Applications. 21, 3 (Oct. 2021), 91–100. DOI:https://doi.org/10.25728/assa.2021.21.3.1124.