1. M.I. Belishev, An approach to multidimensional inverse problems for the wave equation. Sov. Math. Dokl. 36, 481–484 (1988)
2. M.I. Belishev, A.S. Blagovestchenskii, Dynamic Inverse Problems of Wave Theory (St-Petersburg University Press, St-Petersburg, 1999)
3. A.S. Blagoveshensky, On the inverse problem in the theory of propagation of seismic waves. Prob. Math. Phys. 1, 68–81 (1966)
4. A.S. Blagoveshensky, One-dimensional inverse problem for a second order hyperbolic equation. Math. Quest. Wave Propagations Theory 2, 85–90 (1969)
5. A.P. Calderón, On an inverse boundary problem, in Seminar on Numerical Analysis and its Applications to Continuum Physics (Soc. Brasiliera de Matematica, Rio de Janeiro, 1980), pp. 61–73