1. K.J. Aström and T. Söderström, Uniqueness of the Maximum Likelihood Estimates of the Parameters of an ARMA model, IEEE Transactions on Automatic Control, AC-19 (1974), 769–773.
2. S. Barnett, A new formulation of the the theorems of Hurwitz, Routh and Sturm, J. Inst. Maths. Applies, 8 (1971), 240–250.
3. S. Barnett, Matrices, polynomials and linear time invariant systems, IEEE Trans. Automat. Control, AC-18 (1973),1–10.
4. [ H. Cramér, Mathematical methods of statistics, Princeton NJ;Princeton University Press, 1951.
5. K. Glover and J.C. Willems, Parametrizations of linear dynamical systems: canonical forms and identifiability, IEEE Transactions on Automatic Control, AC-19 (1974), 640–646.