K. Corradi, I. Katai, and K. S. Comment-on, Gangadhamn's paper entitled "Two claasicallattice point problems, Magyar Tud. Akad. Mat. Fiz. Oszt. K<>zl, pp.17-89, 1967.

E. Grosswald and R. , 1entations of integers as sums of squares, 1985.

J. Hafner, New 0-theoreJTl$ for two classical lattice point problems, Invent. Math, vol.63, pp.11-20, 1981.

G. H. Hardy, On Dirichlet's Divisor Problem, Proc. London Math. Soc. (2) 15, 1916.
DOI : 10.1112/plms/s2-15.1.1

L. K. Hua, Introduction to Number Theory, 1982.

H. L. Montgomery, Fluctuations in the mean of Euler???s phi function, Proc. Indian Acad. Sci (Math. Sci.} 97 {1987), pp.239-245
DOI : 10.1007/BF02837826

G. Szego, Beitr???ge zur Theorie der Laguerreschen Polynome. II: Zahlentheoretische Anwendungen, Mathematische Zeitschrift, vol.25, issue.1, pp.388-404, 1926.
DOI : 10.1007/BF01283847