Textbook
[1] Elementary Number Theory (Lecture Notes)
[2] Chengdong Pan, Elementary Number Theory (In Chinese), (Corrected by Tao Zhan & Jianya Liu), Higher Education Press, 2012.
References
[1] I.M.Vinogradov, Elements of Number Theory, Dover Publications, 1954.
[2] T. Apostol, Introduction to Analytic Number Theory, Springer-Verlag, New York, 1995.
[3] E. Landau, Elementary Number Theory, Translated by J.B.Goodman, AMS CHELSEA PUBLISHING, 1991.