Basic Library List in Number Theory - http://www.maa.org/BLL/numtheory.htm Compiled by the Mathematical Association of America (MAA). This site sub-divides Number Theory into Introductory Texts, Expositions, Elementary Monographs, Primes and Factors, Algebraic Number Theory, Analytic Number Theory, Modular Forms, P-adic Fields, Special Topics, Cryptography, History and Biography and Classic Works.
