1. Russell, D. L., A Unified Boundary Controllability Theory for Hyperbolic and Parabolic Partial Differential Equations, Studies in Applied Mathematics, Vol. 52, pp. 189–221, 1973.
2. Lebeau, G., and Robbiano, L., Contrôle Exacte de l' Équation de la Chaleur, Communications in Partial Differential Equations, Vol. 20, pp. 335–356, 1995.
3. Lecture Notes Series;A. V. Fursikov,1996
4. Imanuvilov, O. Yu., and Yamamoto, M., On Carleman Inequalities for Parabolic Equations in Sobolev Spaces of Negative Order and Exact Controllability for Semilinear Parabolic Equations, Preprint 98-46, Graduate School of Mathematics, University of Tokyo, Tokyo, Japan, 1998.
5. FernÁndez-Cara, E., and Zuazua, E., The Cost of Approximate Controllability for Heat Equations: The Linear Case, Advances in Differential Equations, Vol. 5, pp. 465–514, 2000.