I am struggling to pick out books when it comes to self studying math beyond Calculus.
My situation is as follows. I have taken all math courses at my school (up to Calc BC and AP Stats) and I have scored 5's on all of the exams. I am going to major in math at college next year but I really do enjoy learning in my free time and I am out of material. I have looked at some of the stuff on KhanAcademy, but the videos go really slowly and lack depth, so I would prefer something to read.
The only semi math book I have read for fun was Gödel, Escher, Bach which I greatly enjoyed. I am looking for anything, even if it reads similar to a textbook, that could further advance my mathematical knowledge in any way. Thank you.
EDIT 1: All answers do answer my question to some extent, so I will not be accepting an answer but rather using them all. Please continue to answer this question as I enjoy having more material to read.
Best Answer
Don't read anything too advanced, i.e. you should be able to understand everything, so you don't waste your time.
How to Prove It: A Structured Approach - Velleman
Numbers and Geometry - Stillwell
Calculus - Spivak
Linear Algebra Done Right - Axler