@article{Grytczuk:2009,
author
=
"A.Grytczuk",
title
=
"Upper bound for sum of divisors function and the Riemann hypothesis",
journal
=
"Tsukuba Journal of Mathematics",
volume
=
"Vol. 31",
number
=
"no 1",
pages
=
"67--75",
year
=
"2007",
}