1. G. H. Hardy and E. M. Wright, An Introduction to Theory of Numbers, 5th Edition, Oxford University Press, 1979.
2. I. Niven, H. S. Zuckerman and H. L. Montgomery, An Introduction to the Theory of Numbers, 5th Edition, John Wiley & Sons, 1991.
3. H. Davenport, The Higher Arithmetic, 7th Edition, Cambridge University Press, 1999.
4. A. Backer, A Concise Introduction to the Theory of Numbers, Cambridge University Press, 1984.
5. L. Hua, Introduction to Number Theory, English Translation from Chinese by P. Shiu, Springer-Verlag, 1980.