Maybe this isn't what your looking for, but this is a list for free online books on computer science (via github).
https://github.com/EbookFoundation/free-programming-books
Hi!
Yes. I just found out I said that I covered tkinter before!
... I clearly didn't. I must have been thinking of turtle.
Please just move forward with the lessons. If you have any specific questions, just ask!
Thanks!
Stef