1. Foias, C., Georgiou, T., Smith, M., Robust stability of feedback systems: A geometric approach using the gap metricSIAM J. Cont and Optim.31(b) (1993), 1518–1537.
2. Vidyasagar, M.Control System Synthesis: A Factorization ApproachCambridge, Mass., MIT Press, 1985.
3. Dale, W., Smith, M., Stabilizability and existence of system representations for discrete-time time-varying systemsSIAM J. Cont and Optim.31(b) (1993), 1538–1557.
4. Smith, M.On stabilization and the existence of coprime factorizationsIEEE Trans. Aut. Cont.34 (1989), 1005–1007.
5. Feintuch, A., Coprime factorization of discrete time-varying systemsSystem Control Lett.7 (1986), 49–50.