A Friendly Introduction to Numerical Analysis.

Prime Numbers and the Riemann Hypothesis

Disquisitiones Arithmeticae

Discrete Mathematics: Elementary and Beyond (Undergraduate Texts in Mathematics)

Elementary Number Theory and Its Application, 6th Edition

The Penguin Book of Curious and Interesting Numbers: Revised Edition

Cryptography: Theory and Practice, Fourth Edition (Textbooks in Mathematics)

Fermat's Enigma: The Epic Quest to Solve the World's Greatest Mathematical Problem

An Introduction to Automorphic Representations: With a view toward trace formulae (Graduate Texts in Mathematics, 300)

Introductory Complex Analysis (Dover Books on Mathematics)