1. On the divisor problem;Chowla;Norske Vid. Selsk. Forhdl.,1963
2. J. Furuya, On mean values of error terms related with lattice points in hyperbolic domains, in: Diophantine Problems and Analytic Number Theory (Kyoto, 2002), Sūrikaisekikenkyuusyo Kōkyūroku No. 1319, 2003, pp. 75–84 (in Japanese).
3. S.W. Graham, G. Kolesnik, Van der Corput's Method for Exponential Sums, London Mathematical Society Lecture Note Series 126, Cambridge University Press, Cambridge, 1991.
4. The average order of the arithmetical functions P(x) and Δ(x);Hardy;Proc. London Math. Soc.,1916
5. The distribution and moments of the error term in the Dirichlet divisor problem;Heath-Brown;Acta Arith.,1992