104 number theory problems: from training of the USA IMO teamby T. Andreescu, D. Andrica and Z. Feng, 2007
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, 2009
Competitive math for middle school: algebra, probability, and number theoryby Vinod Krishnamoorthy, 2018
Elementary number theory: primes, congruences, and secrets: a computational approachby William Stein, 2009
Methods of solving number theory problemsby Ellina Grigorieva, 2018
Nuggets of number theory: a visual approachby Roger B. Nelsen, 2018
Number, shape & symmetryby Diane L. Herrmann and Paul J. Sally, Jr., 2013
Number theory in science and communication (5th ed.)by Manfred R. Schroeder, 2009
Problem-solving and selected topics in number theoryby Michael Th. Rassias, 2011
Problems from the discrete to the continuous: probability, number theory, graph theory, and combinationsby Ross G. Pinsky, 2014
