ДЕСЯТЬ ЛЕТ ПЛАТНОГО ПРИРОДОПОЛЬЗОВАНИЯ В ЭСТОНИИ. ENVIRONMENT. TECHNOLOGY. RESOURCES. Proceedings of the International Scientific and Practical Conference, [S. l.], v. 1, p. 152–155, 1999. DOI: 10.17770/etr1999vol1.1885. Disponível em: https://archive-journals.rtu.lv/etr/article/view/3444.. Acesso em: 11 mar. 2026.