[1] E. Fornasini, G. Marchesini: Doubly indexed dynamical systems: state space models and structural properties. Math. Systems Theory 12 (1978), 59 - 75. MR 0510621 | Zbl 0392.93034

[2] M. Bisiacco, E. Fornasini: Optimal control of 2D systems. SIAM J. Control Optim. 28 (1990), 3, 582 - 601. MR 1047425

[3] J. P. Guiver, N. K. Bose: Causal ane weakly causal 2D filters with applications in stabilization. In: Multidimensional System Theory, Reidel , Dordrecht 1985, pp. 52 -100.

[4] T. S. Huang: Stability of two-dimensional recursive filters. IEEE Trans. Audio Elec. AU-20 (1972), 158 - 163. MR 0392180