Unsolved Problems in Number Theory (Unsolved Problems in Intuitive Mathematics)

Problem Books in Mathematics: Unsolved Problems in Number Theory by Richard...

Unsolved Problems in Number Theory (Problem Books in Mathematics), Guy, Richard,

Unsolved Problems in Number Theory (Unsolved Problems in Intuitive Mathematics)

Ams Chelsea Publishing Ser.: Solved and Unsolved Problems in Number Theory by...

Solved and Unsolved Problems in Number Theory, Daniel Shanks

Unsolved Problems in Mathematical Systems and Control Theory by Blondel, Megr...

Problems in Algebraic Number Theory (Graduate Texts in Mathematics, 190)