1. A. S. Alekseev, "Inverse dynamic problems of seismology," in: Some Methods and Algorithms of Interpretation of Geophysical Data [in Russian], Nauka, Moscow (1967), pp. 9?84.
2. A. V. Baev, "One formulation of the inverse boundary-value problem for the wave equation and iterative method of its solution," Dokl. Akad. Nauk SSSR,287, No. 4, 818?821 (1986).
3. A. N. Tikhonov, "Unique solvability of the electrical prospecting problem," Dokl. Akad. Nauk SSSR,19, No. 6, 797?800 (1949).