Hi I am currently learning Digital Signal Processing from Applied Digital Signal Processing by Manolakis and Ingle. However, my background is in mathematics, so I like being shown why an assertion is true. So, in the chapter about the z-transform is where I start seeing this becoming an issue. So, what book can I use to complement Manolakis' and Ingles book? Currently, I am just looking for rigorous proofs of the results in the chapter about the z-transform.