0-CtrlSysEng
Good course materials
Overview
Fourier analysis: (very interesting! Both are good lectures. They used different ways to explain the same theory.)
By Yongle Li李永乐: https://youtu.be/0LuyxzqI3Hk
Laplace Transformation
By Brian Douglas: A graphical explanation
Stability of closed loop control systems
Physics Videos by Eugene Khutoryansky: Laplace Transformation Explained and visualized (also a very good explanation of complex numbers, real/reactive power, etc.)