1. Nonlinear Techniques for Improving Servo Performance;McDonald,1950
2. A Phase Plane Approach to the Design of Saturating Servomechanism;Hopkin;Trans. AIEE,1951
3. Optimal Discontinuous Forcing Terms;Bushaw,1958
4. An Investigation of the Optimum Switching Criteria for Higher Order Servomechanisms;Bogner;Trans. AIEE,1954
5. On the Bang Bang Control Problem;Bellman;Q. Appl. Math.,1956