Introduction To The Theory Of Numbers by Harold N. Shapiro; Mathematics

Introduction to the Theory of Sets (Dover Books on Mathematics) - VERY GOOD

Introduction to the Theory of Games (Dover Books on Mathematics)

An Introduction to Information Theory (Dover Books on Mathematics)

Introduction to the Theory of Sets (Dover Books on Mathematics) by Breuer

Introduction to Graph Theory (Dover Books on Mathematics)

Elementary Theory of Numbers (Dover Books on Mathematics) - VERY GOOD