Proofs: A Long-Form Mathematics Textbook
Jay Cummings
Information Theory, Inference and Learning Algorithms
David J. C. MacKay
How to Prove It: A Structured Approach
Daniel J. Velleman
Introduction to Algorithms, Third Edition
Thomas H. Cormen & Charles E. Leiserson & Ronald L. Rivest & Clifford Stein
The Design of Approximation Algorithms
David P. Williamson & David B. Shmoys