1. Aboul-Atta, O.A., Boerner, W.M.: Vectoral impedance identity for the natural dependence of harmonic fields on closed boundaries. Can. J. Phys. 53(15), 1404–1407 (1975)
2. Adam, A.: Uber den Vergleich der elektromagnetischen Componenten von Observatorien Nagycenk and Tihany an ruhigen tagen (Sq) auf Grund der Daten vom Jahre 1961. Geofizikai Kozlemenyek XVII(1–2), 39–50 (1966)
3. Bahr, K., Olsen, N., Shankland, T.J.: On the combination of the magnetotelluric and the geomagnetic depth sounding method for resolving an electrical conductivity increase at 400 km depth. Geophys. Res. Lett. 20(24), 2937–2940 (1993)
4. Banks, R.J.: Geomagnetic variations and the electrical conductivity of the upper mantle. Geophys. J. R. Astron. Soc. 17, 457–487 (1969)
5. Bates, R.H.T., Boerner, W.M., Dunlop, G.R.: An extended Rytov approximation and its significance for remote sensing and inverse scattering. Opt. Commun. 18(4), 421–423 (1976)