1. ”Robust Control: The Parameter Space Approach”;Ackermann,2002
2. “Design of robust PID controllers using decoupling at singular frequencies.”;Bajcinca;Automatica,1943
3. Bhattacharyya, S. P., Datta, A. and Keel, L. H. ”Linear Control Theory: Structure, Robustness, and Optimization”, CRC Press, 2012.
4. “All stabilizing PID controllers for time delay systems”;Hohenbichler;Automatica,2009
5. Hohenbichler, N. and Abel, D. ”Calculating All KP Admitting Stability of a PID Control Loop”, Proc. of the 17th IFAC World Congress, pages 5802-5807, 2008.