[1] Berezanskii, Ju. M., Gali I. M.: Positive definite functions of infinitely many variables in the layer. Ukrainskii Mat. Zhurnal 24, 4 (1972), 435-464. MR 0380406

[2] Berezanskii, Ju. M.: Self-adjointness of elliptic operators with an infìnite number of variabes. Ukrainskii Mat. Zhurnal 27, 6 (1975), 729-742. MR 0405094

[3] Dubovitskii A., Milyutin A.: Extrernal problems with side conditions. Zhurnal Vychisl. Mat. i Mat. Fyz. 5, 3 (1965), 395-453.

[4] Gali I. M., El-Saify H. A.: Optimal control of a system governed by hyperbolic operator with an infinite number of variables. Journal of Math. Anal. and Appl. 85, (1982), 24-30. MR 0647556 | Zbl 0563.49013

[5] Gali I. M., El-Saify H. A.: Distributed control of a system governed by a self-adjoint elliptic operator with an infinite number of variables. JOTA 39, 2 (1983), 293-298. MR 0693688

[6] Gali I. M., El-Saify H. A.: Optimal control of systems governed by Petrowsky type equation with an infìnite number of variables. Journal of Information and Optimization Sciences 4, 1 (1983), 83-94. MR 0697994 | Zbl 0535.49017

[7] Girsanov I. V.: Lectures on mathematical theory of extremum problems. Springer-Verlag, New Yoгk, 1972. MR 0464021 | Zbl 0234.49016

[8] Ioffe A.D., Tikhomirov V. M.: Theory of extremal problems. North-Holland, Amsteгdam, 1979. MR 0528295 | Zbl 0407.90051

[9] Kotarski W.: Optimal control of a system governed by a parabolic equation with an infìnite number of variables. JOTA 60, 1 (1989), 33-41. MR 0981943 | Zbl 0663.49009

[10] Łędzewicz-Kowalewska U.: Optimal control problems of hyperbolic systems with operator and nonoperator equality constraints. Applicable Analysis 27, 1-3 (1988), 199-215. MR 0922778 | Zbl 0613.49023

[11] Lasiecka I.: Conical approximations of sets with applications to optimization problems. Technical University, Warsaw, 1974, Poland, Ph. D. Thesis (in Polish).

[12] Lions J. L.: Optimal control of systems governed by partial differential equations. Springer-Verlag, New York, 1971. MR 0271512 | Zbl 0203.09001

[13] Walczak S.: Some properties of cones in normed spaces and their application to investigating extremal problems. JOTA 42, 4 (1984), 561-582. MR 0739435 | Zbl 0504.52001

[14] Walczak S.: On some control problem. Acta Univ. Łodziensis, Folia Mathematica 1 (1984), 187-196. MR 0809025 | Zbl 0565.49015