I'm a 17 year old junior looking to further develop my mathematical skills in order to better prepare myself for university level pure mathematics. I'm looking for books/courses in Analysis, Linear Algebra, Discrete Maths, Combinatorics, Statistics or anything that could be helpful. I've already applied to different universities for summer courses but would also like to get more information by people who have studied maths themselves.
Thanks in advance!
You might enjoy Combinatorics Through Guided Discovery.