1. T. Apostol, Introduction to Analytic Number Theory (Springer Verlag, 1974).
2. H. Cohn, Advanced Number Theory (Dover Publication, 1980).
3. R. Bellman, Analytic Number Theory An Introduction (Benjamin-Cummins, 1980).
4. M. R. Murty, Problems in Analytic Number Theory (Springer, 1999).
5. S. S. Rau and B. Uma, Square-free ideals and an assertion of Ramanujan, Indian J Pure Appl Math 33(10), 1595–1600 (2002).