Drozdenko, T. et al. 2021. 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, (Jun. 2021), 50–54. DOI:https://doi.org/10.17770/etr2021vol1.6557.