1. Spectral Density Function and Auto-covariance 
--- Wiener-Khintchine Theorem
--- Wold's Theorem
 
2. Spectral Representation of Stationary Processes
--- Continuous-time Processes
--- Discrete-time Processes
--- Application 
 
3. Spectral Density Function for Discrete-time Processes
--- ARMA Processes
--- Application