Haykin and Van Veen have designed Signals and Systems to be appropriate for both one- and two-semester sophomore-junior versions of the Signals and Systems course. The book's integrated, balanced treatment of continuous- and discrete-time forms of signals and systems is both a reflection of the topics' real roles in engineering practice and a clear, practical way of introducing the large range of topics covered by the course. Already known for its extensive example and problem sets, the Second Edition has added even more examples and problems. All chapters have been revised to improve clarity and organization.
Simon Haykin was a Canadian electrical engineer noted for his pioneering work in Adaptive Signal Processing with emphasis on applications to Radar Engineering and Telecom Technology. He was a Distinguished University Professor at McMaster University in Hamilton, Ontario, Canada.
Do not read this book for your introductory course in Signals and Systems. The book is long, verbose, difficult to read and containing unnecessary information (say tons of problems on electricity circuit). You should go for "Schaums Outlines: Signals and Systems".