104 number theory problems: from the training of the USA IMO Teamby T. Andreescu, D. Andrica and Z. Feng, 2007
A friendly introduction to number theory (4th ed.)by Joseph H. Silverman, 2012
An introduction to number theory with cryptography ( 2nd ed.)by James S. Kraft and Lawrence C. Washington, 2018
An introduction to the theory of numbersby G.H Hardy et al., 2008
Competitive math for middle school: algebra, probability, and number theoryby Vinod Krishnamoorthy, 2018
Nuggets of number theory: a visual approachby Roger B. Nelsen, 2018
Number theory: structures, examples, and problemsby Titu Andreescu and Dorin Andrica, 2009
Number, shape, and symmetryby Diane L. Herrmann and Paul J. Sally Jr., 2012
Pure mathematics for beginnersby Dr. Steve Warner, 2018
Pure mathematics for beginners: solution guideby Dr. Steve Warner, 2018
