1. Analytic properties of the Schmidt pairs of a Hankel operator and the generalized Schur–Takagi problem;Adamjan;Matematicheski\u\i Sbornik. Novaya Seriya,1971
2. On the approximation of delay elements by feedback;Batlle;Automatica Journal of IFAC,2000
3. Approximating delay elements by feedback;Beghi;IEEE Transactions on Circuits Systems I,1997
4. Bellman, R., & Cooke, K. L. (1963). Differential-difference equations. New York: Academic Press.
5. Curtain, R. F., & Zwart, H. (1995). An introduction to infinite-dimensional linear systems theory. New York: Springer-Verlag.