Sproge, Ilze, Irina Curkina, Sandra Jekabsone, Valentina Tsilibina, Julia Rumyantseva, and Kirill Piletsky. “Production and Foreign Trade of Mineral Products in Latvia and Belarus”. ENVIRONMENT. TECHNOLOGIES. RESOURCES. Proceedings of the International Scientific and Practical Conference 1 (August 6, 2015): 240–245. Accessed May 7, 2024. https://journals.ru.lv/index.php/ETR/article/view/830.