This website (https://www.tutorialspoint.com/tutorialslibrary.htm) is a great point for learning by yourself, and it is free. The contents are from a wide range, but especially from computer science and programming. There are also lessons on Mathematics, Control Theory, etc.
![tutorialspoint](http://eduzgun.home.uludag.edu.tr/wp-content/uploads/2019/03/Ekran-Alıntısı-1024x467.png)