Signals and Systems (2nd Edition) 2nd (second) Edition by Oppenheim, Alan V., Willsky, Alan S., Hamid, with S. published by Prentice Hall (1996)

This authoritative book, highly regarded for its intellectual quality and contributions provides a solid foundation and life-long reference for anyone studying the most important methods of modern signal and system analysis. The major changes of the revision are reorganization of chapter material and the addition of a much wider range of difficulties.