1. J. S. Bendat and A. G. Piersol,Engineering Applications of Correlation and Spectral Analysis, John Wiley, New York, 1980.
2. W. R. Bennett, Statistics of regenerative digital transmission.,Bell System Tech. J., 37, 1501?1542, 1958.
3. H. D. D'Angelo,Linear Time-Varying Systems: Analysis and Synthesis, Allyn & Bacon, Boston, MA, 1970.
4. B. A. Francis and T. T. Georgiou, Stability theory for linear time-invariant plants with periodic digital controllers,IEEE Trans. Auto. Control, 33, 820?832, 1988.
5. W. A. Gardner,Introduction to Random Processes, 2nd ed., McGraw-Hill, New York, 1989.