J. Gregor and J. Tišer "On Hadamard Powers of Hurwitz Polynomials", Math. of Control, Signals, and Systems , 1998, No. 11. pp. 372–378.
J. Gregor "The Cauchy Problem for Partial Difference Equations ", Acta Appl. Math., 1998, Vol. 53., No. 3. pp. 247–263.
J. Gregor "Towards a General Theory of Discrete Systems", in P. M. Frank (Editor) Advances in Control, Springer Verlag, London, 1999.
J. Gregor "Difference Equations and n-D discrete Systems" In: Proceedings of the Fifteenth International Symposium on Mathematical Theory of Networks and Systems [CD-ROM] . Notre Dame: University of Notre Dame, 2002.
J. Gregor "Continued Fractions and 2D Hurwitz Polynomials" In: Multidimensional Systems and Signal Processing. 2002, vol. 13, no. 2, p. 187–199. ISSN 0923-6082.
J. Gregor "Stability of Non-Convolutional n-D Linear Systems", Trans. IEEE Circuits & Systems, I, 2002, Vol. 19, No. 12, December, pp. 1773–1781.
J. Gregor "Partial difference equations and the maximum principle", WSEAS Trans.on Math, Issue I, Vol. 3, January 2004, pp. 192–197.
J. Gregor "The maximum principle and growth estimates for partial difference equations", Aequationes Mathematicae, Vol. 79 (2006), pp. 86–99.
