1. M. I. Belishev, “Boundary control and wave field continuation”, Preprint LOMI P-1-90 (1990).
2. S. A. Avdonin, M. I. Belishev, and S. A. Ivanov, “Boundary control and the inverse matrix problem for the equation ytt−yxx+V(x)y=0”,Mat. Sb.,182, No. 3, 307–331 (1991).
3. M. I. Belishev and Y. V. Kurylev, “Boundary control, wave field continuation, and inverse problems for the wave equation”,Computer Math. Applic.,22, No. 4/5, 27–52 (1991).
4. D. L. Russell, “Controllability and stabilizability theory for linear partial differential equations: recent progress and open questions”,SIAM Rev.,20, No. 4, 639–739 (1978).
5. A. G. Butkovskii,Methods of the Theory of Optimal Control by Distributed Systems [in Russian], Moscow (1975).