number" , Encyclopedia of Mathematics , Springer , ISBN   978-1-55608-010-4 , http://www.encyclopediaofmath.org/index.php?title=p/p074530   Caldwell, Chris, The Prime Pages at primes.utm.edu . Prime Numbers on In Our Time at the BBC . An Introduction to Analytic Number Theory, by Ilan Vardi and Cyril Banderier Plus teacher and student package: prime numbers from Plus,