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[2]   Douglas S. Jones. Acoustic and Electromagnetic Waves. Clarendon Press $\cdot$ Oxford, Oxford University Press, Walton Street, Oxford OX2 6DP, UK, 1986.

[3]   E.W. Leaver. Spectral decomposition of the perturbation response of the schwarzschild geometry. Physical Review D, 34(2), 15 July 1986.

[4]   Ulrich Schmucker and Peter Weidelt. Electromagnetic induction in the earth. Lecture Notes Aarhus, 1975.

[5]   Fiona Simpson and Karsten Bahr. Practical Magnetotellurics. Cambridge University Press, The Edinburgh Building, Cambridge CB2 2RU, UK, and 40 West 20th Street, New York, NY 10011-4211, USA, 2005.

[6]   Michael S. Zhdanov and George V. Keller. The Geolelectrical Methods in Geophysical Exploration. Elsevier Science, Elsevier Science B.V., P.O. Box 521, 1000 AM Amsterdam, The Netherlands, 1994.