1. K.J. Aström and T. Hägglund. Automatic Tuning of PID Controllers. Instrument Society of America, 1988.
2. K.J. Aström and T. Hagglund. Revisiting the ziegler-nichols step response method for pid control. J. Proc. Cont., 14: 635–650, 2004.
3. K.J. Aström and B. Wittenmark. Adaptive Control. Addison-Wesley, New York, 1989.
4. C.T. Chen. Analog and Digital Control System Design: Transfer-Function, State-Space, and Algebraic Methods. Harcourt Brace Jovanovich College, Fort Worth, 1993.
5. J.Y. Choi, H.G. Pandit, R.R. Rhinehart, and R.J. Farrell. A process simulator for pH control studies. Comp. Chem. Engng., 19: 527–539, 1995.