The book is devoted to a systematic consideration of the main problems of the theory of inertial navigation systems, corrected from additional sources of information (from an altimeter, a Doppler speed meter, lag, etc.). The main attention is paid to the study of the error equations of inertial systems in various correction methods. The main purpose of this study is to analyze stability and study the dependence of errors in determining navigation parameters (coordinates, speed, orientation) by the inertial system on instrumental errors of both elements of the inertial system and sources of additional information used for correction...