9-1: Shifting the Unit Step
9-2: Sampling with an Impulse
9-3: Derivative of a Discontinuous Function
9-4: Squaring is Time-Invariant
9-5: Integrator is Time-Invariant
9-6: A Time-Varying System
9-7: Squaring is Nonlinear
9-8: Integrator is Linear
9-9: Convolve Unit Steps
9-10: Convolution with Doublet
9-11: Convolve Impulses
9-12: Impulse Convolution Causes Shifting
9-13: Delay-Integrator Cascade
9-14: Parallel Connection
9-15: Derivative-Integral Cascade
9-16: Stable System
9-17: Unstable System
9-18: Integrator is Unstable
9-19: Non-Causal System
9-20: Flip System not Causal
McClellan, Schafer, and Yoder, Signal Processing First, ISBN 0-13-065562-7.