1. Mounfield, W.P. and Grujić, Lj.T., High-Gain PI Natural Control for Exponential Tracking of Linear Single-Output Systems with State-Space Description, RAIRO-APII, 1992, vol. 26, pp. 125–146.
2. Grujić, Lj.T. and Mounfield, W.P., Natural Tracking PID Process Control for Exponential Tracking, American Inst. Chem. Eng. J., 1992, vol. 38, no. 4, pp. 552–562.
3. Mounfield, W.P. and Grujić, Lj.T., Natural Tracking Control for Exponential Tracking: Lateral High-Gain PI Control of an Aircraft System with State-Space Description, Neural, Parallel and Scientific Computations, 1993, vol. 1, no. 3, pp. 357–370.
4. Mounfield, W.P. and Grujić, Lj.T., High-Gain PI Natural Tracking Control for Exponential Tracking of Linear MIMO Systems with State-Space Description, Int. J. Systems Science, 1994, vol. 25, no. 11, pp. 1793–1817.
5. Grujić, Lj.T. and Mounfield, W.P., Natural PD Exponential Tracking Control: State-Space Approach to Linear Systems, Proc. The Cairo Third IASTED Int. Conf. Computer Applications in Industry, Cairo, Egypt, December 26–29, 1994, pp. 432–435.