Guseynov, S.E. and Rimshans, J.S. 2017. ON THE GINZBURG-FEINBERG PROBLEM OF FREQUENCY ELECTROMAGNETIC SOUNDING FOR UNAMBIGUOUS DETERMINATION OF THE ELECTRON DENSITY IN THE IONOSPHERE. ENVIRONMENT. TECHNOLOGIES. RESOURCES. Proceedings of the International Scientific and Practical Conference. 3, (Jun. 2017), 89–96. DOI:https://doi.org/10.17770/etr2017vol3.2561.