Andreas Antonopoulos has some books about Bitcoin.
Mastering Bitcoin (2nd edition, free to read on Github).

Webtricks has some educational topics.
How to create Blockchain? Build your own chain (Easy-Peasy Guide)
[Full Guide+Code]Seed Phrase & The Process of Deriving Bitcoin Addresses from It
A quick guide on `How the hash of Bitcoin block is calculated?
What is Elliptic Curve Cryptography? Understand how is it related to Bitcoin.
How Bitcoin Addresses are generated? Understand the Math behind Bitcoin