http://web.eecs.umich.edu/~fessler/course/451/l/pdf/c3.pdf

http://math.fullerton.edu/mathews/c2003/ZTransformIntroMod.html

http://dea.brunel.ac.uk/cmsp/Home_Saeed_Vaseghi/Chapter04-Z-Transform.pdf

http://books.google.com/books?id=uHs7gpNKqTEC&source=gbs_similarbooks

http://books.google.com/books/about/An_introduction_to_the_Laplace_transform.html?id=UU7vAAAAMAAJ

http://my.safaribooksonline.com/book/electrical-engineering/computer-engineering/9780123740908/chapter-5-the-z-transform/chapter_5_the_ztransform#X2ludGVybmFsX0J2ZGVwRmxhc2hSZWFkZXI/eG1saWQ9OTc4MDEyMzc0MDkwOC8xNTY=