Metlāns, Aigars, and Edmunds Teirumnieks. “EAST LATGALE SAA PROJECT”. ENVIRONMENT. TECHNOLOGIES. RESOURCES. Proceedings of the International Scientific and Practical Conference 1 (June 20, 2001): 80–84. Accessed May 5, 2024. https://journals.rta.lv/index.php/ETR/article/view/1940.