Efrosima Zaneva-Dobranova, Nikolay Hristov. NEW OPPORTUNITIES FOR ENERGY STORAGE IN BULGARIA - PROMISING HYDROGEN TECHNOLOGIES. SGEM International Multidisciplinary Scientific GeoConference EXPO Proceedings; 21st SGEM International Multidisciplinary Scientific GeoConference Proceedings 2021, Science and Technologies in Geology, Exploration And Mining, 2021, pp. 535-542. https://doi.org/10.5593/sgem2021/1.1/s05.097