1. Fundamental Theory of Automatic Linear Feedback Control Systems;Horowitz;IRE Trans. on Automatic Control,1959
2. A New Approach to the Sensitivity Problem in Multivariable Feedback System Design;Cruz;IEE Trans. on Automatic Control,1964
3. The Parameter Variation Problem in State Feedback Control Systems;Perkins,1964
4. I.M. Horowitz, Ibid., pp. 441-448