Purmalis, O., Kļaviņš, L. and Arbidans, L. (2019) “COMPOSITION AND QUALITY OF FRESHWATER LAKE SEDIMENTS (BALVU AND PĒRKONU LAKES)”, ENVIRONMENT. TECHNOLOGY. RESOURCES. Proceedings of the International Scientific and Practical Conference, 1, pp. 229–235. doi:10.17770/etr2019vol1.4129.