Ask HN: Books that make daunting subjects, accessible (examples inside)

Hey, HN!

I want more examples of books that explain daunting, technical subjects like Grokking Algorithms [0] does for computer science algorithms and data structures or Calculus Made Easy for Calculus [1].

Does anyone else have examples of books in this vein?

[0] https://www.manning.com/books/grokking-algorithms [1] http://calculusmadeeasy.org