Garrity's "All the Math You Missed". Brings you up to speed fast, and has great references.
In logic, "Introduction to Logic: and to the Methodology of Deductive Sciences" - Tarski.
I wish that I started studying these three books before college, in order: 1) Tarski's 2) Strang's 3) Jaynes'
Garrity's "All the Math You Missed". Brings you up to speed fast, and has great references.