1. Sharp sufficient conditions for the observation, control, and stabilization of waves from the boundary;Bardos;SIAM J. Control and Optimization,1992
2. Global uniqueness of a class of multidimensional inverse problems;Bukhgeim;Soviet Math. Dokl.,1981
3. Observabilité frontière de l'équation des ondes;Ho;C. R. Acad. Sci. Paris Sér. I Math.,1986
4. Inverse Source Problems;Isakov,1990