GAMMA-BACKGROUND RADIATION CONTROL SYSTEMS AS A FACTOR OF BULGARIA’S NATIONAL SECURITY. ENVIRONMENT. TECHNOLOGY. RESOURCES. Proceedings of the International Scientific and Practical Conference, [S. l.], v. 4, p. 83–88, 2024. DOI: 10.17770/etr2024vol4.8225. Disponível em: https://archive-journals.rtu.lv/etr/article/view/5095.. Acesso em: 11 mar. 2026.