1. Kushner, H. J., IEEE Int. Conv. Rec. 14, 143 (1966).
2. Astrom, K.J., "Introduction to Stochastic Control Theory." Academic Press, New York (1970).
3. Lur'e, A.I., "Some Nonlinear Problems in the Theory of Automatic Control" (in Russian). Gostekhizdat, Moscow (1951). German translation, Akademie Verlag (1957). English translation, Her Majesty's Stationary Office (1957).
4. LaSalle, J.P., SIAM J. Contr. 1, 3 (1962).
5. Kalman, R.E., and Bertram, J.E., J. Basic Engineering 82, 371 (1960).