Попкова, Л. И., and А. С. Овсянников. “Territorial Differences in the Level of Food Security in the Regions of the Central Black Soil Region”. Proceedings of Voronezh State University. Series: Geography. Geoecology, no. 2, Apr. 2019, pp. 5-16, doi:10.17308/geo.2019.2/2296.