Preslav Peev, Bogdan Prodanov. "APOLLONIA PONTICA DURING THE AGES. FUTURE RESEARCH PERSPECTIVES." SGEM International Multidisciplinary Scientific GeoConference- EXPO Proceedings; 23rd International Multidisciplinary Scientific GeoConference Proceedings SGEM2023, Science and Technologies in Geology, Exploration And Mining, Vol 23, Issue 1.1 (2023): 11-18. https://doi.org/10.5593/sgem2023/1.1/s01.02