1. G. Basile and G. Marro, Controlled and conditioned invariants in linear system theory, Prentice-Hall, 1992.
2. Controlled and conditioned invariant subspaces in linear system theory
3. I. M. Buzurovic, “Geometric approach to the study of thge linear singular systems,” MS Thesis, Belgrade 2000.
4. On the geometry of the set of controllability subspaces of a pair (A,B)
5. Z. Sun and S. S. Ge, Switched Linear Systems: Control and Design, (Springer Verlag, London, 2005).