Hilbert's Ten Problem

https://www.math.washington.edu/~morrow/336_15/papers/andrew.pdf

http://math.stanford.edu/~lekheng/flt/wiles.pdf   

https://en.wikipedia.org/wiki/Diophantine_equation

https://en.wikipedia.org/wiki/Goldbach's_conjecture

http://sweet.ua.pt/tos/goldbach.html

https://arxiv.org/pdf/math/0309103.pdf

MAA Contest Problem Book IV:

http://files.eric.ed.gov/fulltext/ED239856.pdf