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3. D. P. Zidarov, About Solution Some Inverse Problems for Potential Fields and it Use for Geophysical Problems (BAS, Sofia, 1980).
4. V. N. Strakhov, ‘‘For theory of plane problems of gravimetry and magnetometry—’analitical universe’ is generated by Poincare balayage,’’ Izv. Akad. Nauk SSSR, Fiz. Zemli, No. 2, 47–73 (1978).
5. V. G. Filatov, ‘‘Soluting direct problem and inverse problem of gravimetry for two contact bounderies by balayage, concentration and non-linear programming,’’ Izv. Akad. Nauk SSSR, Fiz. Zemli, No. 5, 93–98 (1980).