What is the best book ever published on university level maths?

David N: What is the best book ever published on university level maths?
What is the best book ever published on university level maths? Any why?

Answers and Views:

Answer by Jeff
Here’s a great book

Fundamentals of Mathematics (Paperback)
~ Moses Richardson (Author)

Answer by Brian
I really enjoyed both Introduction to Analysis by Edward Gaughan and Abstract Algebra by David Dummit and Richard Foote. They’re both fantastic at explaining their respective subjects.