IMPROVED UNDERGROUND MINING DESIGN METHOD FOR ESTONIAN OIL SHALE DEPOSIT. ENVIRONMENT. TECHNOLOGY. RESOURCES. Proceedings of the International Scientific and Practical Conference, [S. l.], v. 1, p. 270–274, 2005. DOI: 10.17770/etr2005vol1.2140. Disponível em: https://archive-journals.rtu.lv/etr/article/view/3595.. Acesso em: 11 mar. 2026.