1. V. G. Romanov, “On the uniqueness of the definition of an isotropic Riemannian metric inside a domain in terms of the distances between points of the boundary,” Dokl. Akad. Nauk SSSR,218, No. 2, 295–297 (1974).
2. R. G. Mukhometov, “The problem of the recovery of a two-dimensional Riemann metric and integral geometry,” Dokl. Akad. Nauk SSSR,232, No. 1, 32–35 (1977).
3. R. G. Mukhometov, “The inverse kinematic problem of seismology on the plane,” in: Mathematical Problems of Geophysics (collection of papers of the Computational Center, Siberian Branch, Academy of Sciences of the USSR), No. 6, Part 2 (1975), pp. 243–254.
4. L. Shvarts(Schwartz), Analysis [Russian translation], Vol. 2, Mir, Moscow (1972).