I am looking for suggestions on books to use for self study over the summer. I'm just finishing my first year calculus class intended for math majors. We've used Stewart, and I've enjoyed it. I've also taken statistics for economics, and a mathematical economics class.
With what I've learned so far, what would be a good next step? I will be taking Linear Algebra in the fall. I've bought How to Prove It: A Structured Approach, and I will be reading it and going through it carefully. What else is open to me based on my current knowledge? It's mainly for interest, but anything that can help me be a better mathematician would be great.