1. B. D. O. Anderson, J. B. Moore,Linear Optimal Control, Prentice Hall, Englewood Cliffs, New Jersey, 1971.
2. A. V. Balakrishnan, Stochastic Filtering and Control of Linear Systems: A General Theory,Control Theory of Systems Governed by Partial Differential Equations, Academic Press, New York, 1977.
3. A. V. Balakrishnan,Applied Functional Analysis, Springer-Verlag, New York, 1976.
4. A. V. Balakrishnan, J. L. Lions, State Estimation for Infinite Dimensional Systems,J. Computer and Systems Sciences, 1, 391–403, (1967).
5. J. F. Barrett, Construction of Linear Quadratic Regulators Using Spectral Factorization and the Return Difference Matrix,Techn. Report CN/75/4, The University of Cambridge, May 1975.