1. J. Duda: Parametric optimization problem for systems with time delay. PhD thesis, AGH University of Science and Technology, Krakow, Poland, 1986.
2. Parametric optimization of neutral linear system with respect to the general quadratic performance index;J. Duda;Archiwum Automatyki i Telemechaniki,1988
3. Lyapunov functional for a linear system with two delays;J. Duda;Control and Cybernetics,2009
4. New Lyapunov-Krasovskii functionals for stability of linear retarded and neutral type systems;E. Fridman;Systems & Control Letters,2001