Drozdenko, Tatyana, Sergey Fedorov, and Irina Kek. “SEASONAL DYNAMICS OF PHYTOPLANKTON AND SOME HYDROCHEMICAL INDICATORS OF THE PEIPSI-PSKOV LAKE”. ENVIRONMENT. TECHNOLOGIES. RESOURCES. Proceedings of the International Scientific and Practical Conference 1 (June 16, 2021): 50–54. Accessed May 3, 2024. https://journals.rta.lv/index.php/ETR/article/view/6557.