1. “Perturbation Theory for Linear Operators,”;Kato,1966
2. “Linear Operator Theory in Engineering and Science,”;Naylor,1971
3. “Partial Differential Equations,”;Friedman,1969
4. “On Complete Controllability of Linear Systems,”;Fattorini;J. Diff. Eqs.,1967
5. “Exact Controllability Theorems for Linear Parabolic Equations in One Space Dimension,”;Fattorini;Arch. Rational Mech. Anal.,1971