Daniela Zlatunova. AIR QUALITY MANAGEMENT IN THE BORDER REGION OF THE REPUBLIC OF BULGARIA AND THE REPUBLIC OF SERBIA. SGEM International Multidisciplinary Scientific GeoConference EXPO Proceedings; 20th International Multidisciplinary Scientific GeoConference Proceedings SGEM 2020, Energy and Clean Technologies, 2020, pp. 297-304. https://doi.org/10.5593/sgem2020/4.1/s19.037