01/07 This title is now available from Walter de Gruyter. Please see www.degruyter.com for more information. The problems of determining coefficients of hyperbolic equations and systems from additional information on their solutions are of great practical significance. As a rule, the desired coefficients are important characteristics of the media under consideration. In this monograph, dynamic type of inverse problems in which the additional information is given by the trace of the direct problem solution on a (usually time-like) surface of the domain is considered. In this book theoretical and numerical background of the direct methods are discussed. Theorems of convergence, conditional stability and other properties of the mentioned above methods are formulated and proven.