“…(i) the uniqueness and the stability in determining coefficients: Especially for parabolic equations, see Benabdallah, Dermenjian and Le Rousseau [5], Benabdallah, Gaitan and Le Rousseau [6], Imanuvilov and Yamamoto [15], [17], Imanuvilov, Puel and Yamamoto [19], Isakov [21], Klibanov [23], [24] Klibanov and Timonov [26], Yuan and Yamamoto [32] and the references therein. For hyperbolic problems, among many works, we restrict ourselves to a few works such as Imanuvilov and Yamamoto [16], Isakov [20], [21], Klibanov [23], Klibanov and Timonov [26] and see the references also in Isakov [21] and Klibanov and Timonov [26].…”