Calculus

This is the book that separates the math enthusiasts from the math tourists. Spivak's approach is legendarily thorough, building calculus from the ground up with crystal-clear logic and elegant proofs. While not for the faint of heart, it's the preferred choice for honors students and anyone who wants to truly understand the 'why' behind calculus. Master this book, and you'll have a deeper understanding of calculus than 99% of your peers.