1. Bellman R. and Kalaba R.: Mathematical Trends in Control Theory, Dover, New York, 1964.
2. Maxwell J. Clerk: Proc. Roy. Soc. 16 (1868), 270.
3. Hurwitz A.: Math. Annalen. 46 (1895), 273. (English Translation in Bellman, op. cit. p. 4)
4. Barnett S.: Introduction to Mathematical Control Theory, Clarendon, Oxford, 1975.
5. Davis M. H. A.: Linear Estimation and Control, Chapman and Hall, London, 1977.