Here is another example
https://gist.github.com/justinmeiners/0aff3d98a66b4d5f109656...
> Does the book cover all the relevant parts
No, it isn't quite so comprehensive, but it will absolutely help you get started and help you decide if you want to learn more.
https://www.amazon.com/Introduction-Graph-Theory-Dover-Mathe...
Start with some liberal-arts introduction to a particular topic of interest and delve in.
I often find myself recommending Introduction to Graph Theory [0]. It is primarily aimed at liberal arts people who are math curious but may have been damaged or put off by the typical pedagogy of western mathematics. It will start you off by introducing some basic material and have you writing proofs in a simplistic style early on. I find the idea of convincing yourself it works is a better approach to teaching than to simply memorize formulas.
Another thing to ask yourself is, what will I gain from this? Mathematics requires a sustained focus and long-term practice. Part of it is rote memorization. It helps to maintain your motivation if you have a reason, a driving reason, to continue this practice. Even if it's simply a love of mathematics itself.
For me it was graphics at first... and today it's formal proofs and type theory.
Mathematics is beautiful. I'm glad we have it.
[0] https://www.amazon.com/Introduction-Graph-Theory-Dover-Mathe...
Update: I also recommend keeping a journal of your progress. It will be helpful to revisit later when you begin to forget older topics and will help you to create a system for keeping your knowledge fresh as you progress to more advanced topics.
If you're a liberal-arts kind of person and or have scars from prior experiences with mathematics I recommend, https://www.amazon.com/Introduction-Graph-Theory-Dover-Mathe...
A Logical Approach to Discrete Mathematics: https://www.amazon.com/Logical-Approach-Discrete-Monographs-...
And a more pragmatic approach to the same material (with a lot of cross-over in terms of proof-style, etc):
Programming in the 1990s: http://www.springer.com/gp/book/9780387973821
But one I particularly enjoyed early on was written for liberal-arts level students of maths (who might've been traumatized by maths in the past):
Introduction to Graph Theory: https://www.amazon.com/Introduction-Graph-Theory-Dover-Mathe...
It will actually get you into writing proofs in set theory within the first couple of chapters.
"A stimulating excursion into pure mathematics aimed at "the mathematically traumatized," but great fun for mathematical hobbyists and serious mathematicians as well. Requiring only high school algebra as mathematical background, the book leads the reader from simple graphs through planar graphs, Euler's formula, Platonic graphs, coloring, the genus of a graph, Euler walks, Hamilton walks, and a discussion of The Seven Bridges of Konigsberg."
The standard pedagogy is algebra then calculus by the end of HS. For me it was learning to program computers by way of making video games that solidified my understanding of HS level geometry, trig, and calculus. That was so long ago though that I don't really have any recommendations for current courses or books to go that route. I would recommend learning enough Javascript or something to get a canvas up in your browser and start making boxes move around, accelerate, rotate, follow your mouse, etc. It doesn't have to be anything sophisticated but it can teach you a lot.
If you're eager and enjoy a challenge I'd say my one regret was not learning how to construct my own proofs until much later on. Learning how to apply maths to solve problems is a lot of fun but learning how to think abstractly and make your own arguments is much more satisfying. There's a great book that doesn't require too much more than HS level math to understand which starts to make this connection called, Introduction To Graph Theory [0] and it's one of my all-time favorites.
[0] https://www.amazon.com/Introduction-Graph-Theory-Dover-Mathe...