[1] D. G. Luenberger: An introduction to observers. IEEE Trans. Automat. Control AC-16 (1971), 596-602.

[2] V. Kučera P. Zagalak: Constant solutions of polynomial equations. Internat. J. Control 53 (1991), 495-502. MR 1091157

[3] M. Malabre V. Kučera P. Zagalak: Reachability and controllability indices for linear descriptor systems. Systems Control Lett. 15 (1990), 119-123. MR 1068917

[4] P. Zagalak J. J. Loiseau: Invariant factors assignment in linear systems. In: Proc. SINS'92, ARRI, Ft. Worth 1992, pp. 197-204.

[5] C. C. Tsui: A complete analytical solution to the equation $TA - FT = LC$ and its applications. IEEE Trans. Automat. Control AC-32 (1987), 3, 742-744. MR 0896839 | Zbl 0617.93009

[6] P. Van Dooren: The generalized eigenstructure problem in linear system theory. IEEE Trans. Automat. Control AC-26 (1981), 111-129. MR 0609253 | Zbl 0462.93013

[7] P. Van Dooren: The computation of Kronecker's canonical form of a singular system. Linear Algebra Appl. 27 (1979), 103-140. MR 0545726

[8] P. Van Dooren: Reduced-order observers: A new algorithm and proof. Systems Control Lett. 4 (1984), 243-250. Zbl 0542.93018

[9] V. L. Syrmos P. Zagalak: Computing normal external descriptions and feedback design. Linear Algebra Appl. 188, 189 (1993), 613-639. MR 1223474