Kirilova, Krasimira. “OPTIMAL GEOPOTENTIAL MODELS OF THE EARTH’S GRAVITATIONAL FIELD FOR THE TERRITORY OF SOUTHWESTERN BULGARIA - RILA MOUNTAIN: OPTIMAL GEOPOTENTIAL MODELS OF THE EARTH’S GRAVITATIONAL FIELD FOR THE TERRITORY OF SOUTHWESTERN BULGARIA - RILA MOUNTAIN”. JOURNAL SCIENTIFIC AND APPLIED RESEARCH 19, no. 1 (March 23, 2023): 67–71. Accessed November 22, 2024. https://jsar.ftn.shu.bg/ojs-3.3.0-7/index.php/jsar/article/view/295.