We consider the inverse problem of reconstructing an unknown coefficient in a second order hyperbolic equation from partial (on part of the boundary) dynamic boundary measurements. In this paper we prove that the knowledge of the partial Cauchy data for this class of hyperbolic PDE on any open subset
"On an Inverse Problem of Reconstructing an Unknown Coefficient in a Second Order Hyperbolic Equation from Partial Boundary Measurements." Methods Appl. Anal. 17 (4) 433 - 444, December 2010.