@article{oai:tsukuba.repo.nii.ac.jp:00029817,
 author = {Grytczuk, Aleksander},
 issue = {1},
 journal = {Tsukuba Journal of Mathematics},
 month = {Jun},
 pages = {67--75},
 title = {Upper bound for sum of divisors function and the Riemann hypothesis},
 volume = {31},
 year = {2007}
}