Kliment Naydenov. "BULGARIAN CASE STUDIES IN IMPROVING URBAN AIR QUALITY." SGEM International Multidisciplinary Scientific GeoConference- EXPO Proceedings; 22nd SGEM International Multidisciplinary Scientific GeoConference Proceedings 2022, Energy and Clean Technologies (2022): 287-294. https://doi.org/10.5593/sgem2022/4.1/s19.37