Klibanov, M.V., and A. Timonov. 2003. “A Globally Convergent Convexification Algorithm for the Inverse Problem of Electromagnetic Frequency Sounding in One Dimension”. Numerical Methods and Programming (Vychislitel’nye Metody I Programmirovanie) 4 (4):52-81. https://en.num-meth.ru/index.php/journal/article/view/76.