Shimelevich , M. “On the Method of Calculating the Modulus of Continuity of the Inverse Operator and Its Modifications With Application to Non-Linear Problems of Geoelectrics”. Numerical Methods and Programming (Vychislitel’nye Metody I Programmirovanie), vol. 21, no. 66, Nov. 2020, pp. 350-72, doi:10.26089/NumMet.v21r430.