The Higher Arithmetic: An Introduction to the Theory of Numbers by H. Davenport

Theory of Functions, Parts I and II (Dover Books on Mathematics)

Mathematical Proofs: A Transition to Advanced Mathematics (2nd Edition)

Introduction to the Theory of Numbers by Herbert S. Zuckerman and Ivan Niven

The Colorado Mathematical Olympiad and Further Explorations : Fro

Theory of Algebraic Numbers from Lectures by Emil Artin

a friendly introduction to number theory fourth edition pearson

Mathematical Snapshots - 3rd American Edition by Steinhaus Free Ship 1969 OOP